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Abstract

The Boomerang Lake unconformity-type uranium prospect is located in the Proterozoic western Thelon basin, Canada. Based on geological similarities to other uranium-producing Proterozoic basins, it represents a prospective target for uranium exploration. The potential of the western Thelon basin at Boomerang Lake to host high-grade, unconformity-type uranium deposits has been evaluated using alteration mineral paragenesis and chemistry, stable isotope geochemistry, 40Ar/39Ar geochronology, and a 2 percent HNO3 leach method.

Pre-Thelon basin basement rocks were subaerially weathered by low δ18O value meteoric waters at 1758 ± 7 Ma. Early diagenesis in the basin occurred at ca. 1667 Ma and is marked by a phosphate-dominated alteration mineral assemblage that formed from relatively reducing basinal fluids. Later peak diagenetic basinal fluids produced a widespread phyllosilicate-dominated mineral assemblage at temperatures of as much as 250°C, and had δ18O and δ2H values and chemical compositions consistent with those of oxidizing, saline basinal brines in other uranium-producing Proterozoic basins. Uranium mineralization is associated with hydrothermal alteration by 18O- and 2H-rich evolved basinal fluids at 200°C, but consists of minor amounts of the U+4 phosphate mineral tristramite. The distribution and stable isotope compositions of peak diagenetic and hydrothermal phyllosilicates indicate sandstones overlying the Boomerang Lake prospect were isolated from peak diagenetic basinal fluids that were capable of transporting uranium, resulting in the diminutive uranium phosphate mineralization.

Radiogenic mobile Pb is present in sandstones and basement rocks at Boomerang Lake, but was predominantly produced in situ from U-bearing accessory and detrital minerals and probably not from an undiscovered uranium deposit at depth. The use of 238U/206Pb and (Zr+Th)/U ratios proved to be helpful in evaluating the prospectivity of anomalously radiogenic zones in the Thelon basin.

Introduction

The Paleoproterozoic Thelon basin, Northwest Territories and Nunavut, Canada, remains underexplored for unconformity-related uranium deposits despite geological similarities to the world-class uranium-producing Athabasca basin. At present, the Thelon basin is only known to host unconformity-related uranium mineralization in two areas. The Kiggavik deposit is located just beyond the southern margin of the eastern Thelon basin, Nunavut, and contains reserves of 18,100 tonnes (t) U3O8 at 0.6 percent (Fuchs and Hilger, 1989). Uranium mineralization at the Boomerang Lake prospect is located at the western margin of the western Thelon basin in the Northwest Territories, about 500 km east of Yellowknife (Fig. 1).

The Boomerang Lake uranium prospect shares a geological and structural setting similar to those of sandstone-hosted, complex-type (Fayek and Kyser, 1997) unconformity-related uranium deposits, such as Cigar Lake and McArthur River in the Athabasca basin. It is located at the faulted unconformable contact between early Paleoproterozoic graphitic metasedimentary basement rocks and unmetamorphosed conglomerates and sandstones of the middle to late Paleoproterozoic Thelon Formation (Davidson and Gandhi, 1989). These prospective geological characteristics have established the Boomerang Lake prospect as a high-priority target for unconformity-related uranium deposits in the Thelon basin.

The purpose of this study is to evaluate the potential of the western Thelon basin at Boomerang Lake to host high-grade unconformity-related uranium deposits, building on initial studies by Davidson and Gandhi (1989) and Gandhi (1989). The fluid evolution of basement and basinal rocks is examined, as models of unconformity-related uranium deposits require a protracted fluid history (Kyser and Cuney, 2008a). We present a paragenesis that details the relative timing of alteration minerals and constrains the nature and origin of the fluids in equilibrium with these minerals through stable isotope geochemistry. The absolute timing of alteration mineral formation and subsequent fluid events is determined by 40Ar/39Ar geochronology. In addition, we evaluate the U and Pb isotope compositions and mobile element concentrations as exploration tools.

Geological Setting

Exploration at Boomerang Lake in the western Thelon basin has focused on two electromagnetic conductors, which are referred to as the F- and G-trends, respectively (Fig. 2). The two trends are oriented northeast-southwest and correspond to the regional strike of foliation.

The oldest rocks at Boomerang Lake were intersected along the G-trend and are Late Archean gneissic granitoids of the Rae domain, which forms part of the western Churchill Province (Fraser and Miller, 2007). The equigranular gneiss consists of quartz + K-feldspar + biotite, with zircon and monazite being common accessory minerals. Along the G-trend, the gneissic granitoids are structurally overlain by a package of metasedimentary rocks. The contact between the two units is a zone of mylonite that is several meters thick. The metasedimentary package is dominated by quartz + muscovite schist, with lesser amounts of quartzite and sulfide-bearing schist. Mineral assemblages and textures suggest that the package experienced greenschist-grade metamorphism. These lithologies are correlated with the quartzite-dominated Eyeberry inlier, which lies along strike approximately 40 km to the northwest, and they bear stratigraphic resemblance to the lower parts of the 2.4 to 1.9 Ga Amer Group (Tella et al., 1983).

Fig. 1.

Generalized geological map of the Western Churchill province, Canada, showing the location of the Boomerang Lake unconformity-type uranium prospect in the western Thelon basin. Modified from Davidson and Gandhi (1989). AB = Alberta, MB = Manitoba, NT = Northwest Territories, NU = Nunavut, SK = Saskatchewan.

Fig. 1.

Generalized geological map of the Western Churchill province, Canada, showing the location of the Boomerang Lake unconformity-type uranium prospect in the western Thelon basin. Modified from Davidson and Gandhi (1989). AB = Alberta, MB = Manitoba, NT = Northwest Territories, NU = Nunavut, SK = Saskatchewan.

Fig. 2.

Generalized geological map of the Boomerang Lake uranium prospect. The F- and G-trends are the primary exploration corridors and are defined by the axes of electromagnetic (EM) conductors. Labeled drill holes were used in this study. Stratigraphic sections were measured at drill hole locations shown as a black dot. The Boomerang Lake discovery zone is located near the southwestern end of F-trend. Int. = intermediate.

Fig. 2.

Generalized geological map of the Boomerang Lake uranium prospect. The F- and G-trends are the primary exploration corridors and are defined by the axes of electromagnetic (EM) conductors. Labeled drill holes were used in this study. Stratigraphic sections were measured at drill hole locations shown as a black dot. The Boomerang Lake discovery zone is located near the southwestern end of F-trend. Int. = intermediate.

The F-trend is coincident with an approximately 40-km-wide belt of psammitic to pelitic paragneiss that is comprised of quartz + K-feldspar + biotite ± garnet ± graphite gneiss with accessory anhedral rutile, monazite, apatite, and well-rounded zircon, graphitic schist, and pegmatitic quartz + K-feldspar ± muscovite leucosomes. Mineral assemblages and textures suggest amphibolite-grade metamorphism and partial melting of an aluminous and carbonaceous sedimentary rock protolith. The contact between these paragneisses and the gneissic granitoids and metasedimentary rocks of the G-trend has not been observed. The protolith ages of the paragneiss are unknown. However, Fraser and Miller (2007) suggested the 2.13 to 2.08 Ga Rutledge River paragneisses or rocks of the ca. 2.1 to 1.90 Ga Wollaston Group of the southern Hearne Domain as possible correlative units.

Sedimentary fill of the Thelon basin unconformably overlies the metamorphic basement rocks of the F- and G-trends. The Thelon basin is an intracratonic basin that formed in response to regional thermal subsidence implicit in the formation of the similarly aged Athabasca, Amundsen, and Elu basins in northwestern Canada (Rainbird et al., 2003). The Thelon Formation belongs to the Barrensland Group of the Dubawnt Supergroup (Gall et al., 1992), and consists of unmetamorphosed, shallowly dipping sandstones with minor conglomerate and breccia. The sandstones originally contained as much as 10 percent combined feldspar and lithic clasts but were diagenetically altered to the extent that the only remaining phases are quartz, quartzose lithic clasts, diagenetic phyllosilicates, and refractory detrital phases.

Beyer et al. (2008) distinguished three sequence strati-graphic units within the Thelon Formation at Boomerang Lake (Fig. 3), representing deposition in alluvial fan and lacustrine (Sequence 1), alluvial plain (Sequence 2), and braid plain environments (Sequence 3). The depositional age of the Thelon Formation is bracketed by an underlying ca. 1753 Ma fluorite-bearing granite (Miller, 1995), and by 1667 ± 6 Ma authigenic fluorapatite cement in the basal Thelon Formation (Davis et al., 2008), both determined in the eastern Thelon basin. Sandstones of the Thelon Formation and underlying basement rocks are intruded by northwest-trending Mackenzie diabase dikes that have a U-Pb baddeleyite age of 1267 ± 2 Ma (LeCheminant and Heaman, 1989).

The Boomerang Lake uranium prospect, herein referred to as the discovery zone, is located near the southwestern end of the F-trend (Fig. 2) and occurs in fractured, brecciated, and clay-altered sandstones of the Thelon Formation and graphitic metapelitic basement rocks (Davidson and Gandhi, 1989; Gandhi, 1989). Three of 36 exploration holes drilled by Urangesellschaft Canada Ltd. in 1983 intersected intervals of elevated concentrations of U and Au. The best intersection assayed 0.42 percent U and 25 ppm Au over 0.5 m in clay-altered sandstone. Mineralization is associated with Ni + Co ± Cu sulfides, selenides, and arsenides, and anomalous concentrations of Cr, V, and Zn. Selenides in one sample contained 82 ppb Pt and 160 ppb Pd (Davidson and Gandhi, 1989).

Methods

The present study is based on 351 drill core samples of metamorphic basement rocks and basinal sandstones (Figs. 2–4) and 20 surface samples from nine outcrop localities in the western Thelon basin. Additionally, sample material from the Boomerang Lake discovery zone was obtained from the Geological Society of Canada, Ottawa.

Mineral identification and crosscutting relationships were determined in hand sample and in thin section using optical and electron microscopy. Scanning electron microscopy (SEM) was performed on an Amray 1830 instrument at Queen's University, Kingston, and a JEOL JSM-6400 instrument at Carleton University, Ottawa. Qualitative chemical analyses were conduced by energy dispersive X-ray spectrometry (EDS).

Electron microprobe analysis (EPMA) of selected minerals was performed by wavelength dispersive X-ray spectrometry on a Cameca Camebax MBX electron microprobe at Carleton University. An electron beam with a diameter of 5 to 10 μm was used. Analyses are accurate to 1 to 2 percent for major elements (>10 wt %) and 3 to 5 percent for minor elements (>0.5–<5.0 wt %). At low concentrations (<0.1 wt %), relative errors approach 100 percent.

Field identification of phyllosilicates in hand sample was aided by the use of an ASD TerraSpec short wave infrared (SWIR) spectrometer and AusSpec TSG and Grasswood Geoscience Ltd. MinSpec4 software. Phyllosilicates were separated from crushed whole-rock samples by ultrasound disintegration and centrifugation. The separates were subsequently analyzed by X-ray diffraction (XRD) to determine mineralogical composition, Kübler indices (Kübler, 1967) for white mica, and Hinckley indices (Hinckley, 1963) for kaolinite. The XRD was performed using a Philips X-Pert diffractometer at Queen's University.

The oxygen isotope compositions of the phyllosilicate separates were measured using a dual inlet Finnigan MAT 252 isotope ratio mass spectrometer (IRMS) following oxygen extraction using BrF5 (Clayton and Mayeda, 1963). Hydrogen isotope compositions of phyllosilicates were determined using a ThermoFinnigan TC/EA and a Deltaplus XP IRMS. Carbon and oxygen isotope compositions of carbonates were measured using a Thermo Gas Bench II and a Deltaplus XP IRMS. Oxygen and hydrogen isotope ratios are reported in δ notation in units of per mil (‰) relative to Vienna Standard Mean Ocean Water (V-SMOW), whereas carbon isotope ratios are reported relative to the standard Pee Dee Belemnite (PDB). The δ18O and δ2H analyses were reproducible to ±0.2 and ±3 per mil, respectively. Oxygen isotope fractionation factors used throughout this paper are those of Wenner and Taylor (1971) for water-chlorite, O'Neil and Taylor (1969) for water-muscovite, Sheppard and Gilg (1996) for water-kaolinite and water-dickite, and Zheng (1999) for water-dolomite and water-siderite. Hydrogen isotope fractionation factors used are those of Taylor (1974) for water-chlorite, Vennemann and O'Neil (1996) for water-muscovite, and Sheppard and Gilg (1996) for water-kaolinite and water-dickite.

Fig. 3.

Simplified sections of F- and G-trend exploration corridors at Boomerang Lake. a. Longitudinal section of F-trend. b. Longitudinal section of G-trend. Scale is the same as in Figure 3a. c. Cross section of G-trend. Drill hole locations are shown in Figure 2.

Fig. 3.

Simplified sections of F- and G-trend exploration corridors at Boomerang Lake. a. Longitudinal section of F-trend. b. Longitudinal section of G-trend. Scale is the same as in Figure 3a. c. Cross section of G-trend. Drill hole locations are shown in Figure 2.

Temperatures of formation of muscovite were estimated using the variation of the molar fraction of pyrophyllite (XPrl) as determined by EMPA (Cathelineau, 1988). Temperatures of formation of chlorite were estimated using the method of Zang and Fyfe (1995), a variant of the chlorite geothermometer of Cathelineau (1988), as this geothermometer has been successfully employed in several studies in the Athabasca basin of Canada and the Kombolgie sub-basin of Australia (Polito et al., 2004, 2005; Alexandre et al., 2005, 2009; Cloutier, 2009; Cloutier et al., 2009).

Fig. 4.

Cross section of the Boomerang Lake discovery zone. Data compiled from unpublished Urangesellschaft Canada Ltd. and Uravan Minerals Inc. drill logs and Davidson et al. (1998). Drill hole labels in italics were used in this study.

Fig. 4.

Cross section of the Boomerang Lake discovery zone. Data compiled from unpublished Urangesellschaft Canada Ltd. and Uravan Minerals Inc. drill logs and Davidson et al. (1998). Drill hole labels in italics were used in this study.

40Ar/39Ar geochronology was performed at the Rare Gas Geochronology Laboratory, University of Wisconsin-Madison, using methods summarized by Smith et al. (2003). Plateau ages were calculated using not less than 70 percent of 39Ar released and three consecutive steps that overlap in their 1σ error margin. Pseudoplateau ages were defined by 30 to 70 percent of 39Ar released.

The U/Pb and Pb/Pb isotope ratios and concentrations of 54 elements were determined for 163 samples using a 2 percent HNO3 leach followed by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The applied method is described by Holk et al. (2003).

Results

Mineralogy of the Boomerang Lake prospect

Basement rocks and sandstones of the Thelon Formation host diverse suites of phosphate, phyllosilicate, sulfide, and oxide minerals that formed during multiple fluid events associated with (1) retrograde metamorphism, (2) pre-Thelon basin weathering of basement rocks, 3) early diagenesis of sandstones, (4) peak diagenesis of sandstones, and (5) hydrothermal alteration at the unconformity. A paragenesis displaying the relative timing of the minerals is shown in Figure 5. The distribution of key alteration phases and location of samples discussed is given in Figure 6.

Fig. 5.

Paragenesis of minerals associated with retrograde metamorphism and weathering of basement rocks, diagenesis, and hydrothermal alteration. The 1757 Ma age of basement weathering is interpreted from Ar-Ar geochronology (see text for discussion), and the 1667 Ma age of early diagenesis is inferred from Davis et al. (2008). Temperatures shown in black are calculated from EMPA data, and temperatures in gray are inferred (see text for discussion).

Fig. 5.

Paragenesis of minerals associated with retrograde metamorphism and weathering of basement rocks, diagenesis, and hydrothermal alteration. The 1757 Ma age of basement weathering is interpreted from Ar-Ar geochronology (see text for discussion), and the 1667 Ma age of early diagenesis is inferred from Davis et al. (2008). Temperatures shown in black are calculated from EMPA data, and temperatures in gray are inferred (see text for discussion).

Retrograde metamorphism

Chlorite (C0) and coarse-grained muscovite (M0) (Fig. 7a) are the earliest alteration minerals to affect basement rocks at Boomerang Lake, replacing foliation-controlled, prograde metamorphic biotite. The C0 chlorite occurs in some drill core intersections of relatively fresh, nonfractured paragneiss. The M0 muscovite is present from a few tens of meters below the unconformity and downward, but is mainly absent above this zone.

Pre-Thelon basin weathering

Hematite (F0) is variably present for as much as 50 m below the unconformity. It generally decreases in abundance with increasing depth, and preferentially infiltrates biotite-rich zones, faults, fractures, and foliation. Pervasive vermiform to fine-grained kaolinite (K0) (Fig. 7b) replaces prograde metamorphic biotite, garnet, and K-feldspar, crosscuts M0 muscovite, and fills fractures to a depth of several tens of meters below the unconformity in basement rocks.

Discontinuous, maroon, F0-stained dolomite (D0) veins, which are millimeters wide, are present near the base of the F0 hematite-rich zone in the F-trend basement rocks, and crosscut foliation. Fine-grained illite (I0) was observed only in the F-trend basement fault zones, including the discovery zone, where it alters cataclastically deformed fault gouge. The I0 illite is slightly earlier than or coeval with K0 kaolinite, and is distinguishable from M0 muscovite based on grain size. Paragenetic relationships between I0 illite and F0 hematite or D0 dolomite were not observed. The mineral assemblage C0 chlorite + F0 hematite + K0 kaolinite + I0 illite is similar to minerals described by Gall (1994) in the Thelon paleosol at Boomerang Lake. Subaerial weathering also affected refractory accessory phases contained in basement rocks, as suggested by the presence of partially dissolved, F0 hematite-rimmed zircon and monazite showing atypical birefringence.

Fig. 6.

Longitudinal sections of the F- and G-trends at Boomerang Lake, showing the distribution of peak diagenetic phyllosilicates (determined by SWIR spectrometry and XRD), and locations of samples with key geochemical and geochronological characteristics discussed in the text. Fmn. = Formation. Drill hole locations are shown in Figure 2.

Fig. 6.

Longitudinal sections of the F- and G-trends at Boomerang Lake, showing the distribution of peak diagenetic phyllosilicates (determined by SWIR spectrometry and XRD), and locations of samples with key geochemical and geochronological characteristics discussed in the text. Fmn. = Formation. Drill hole locations are shown in Figure 2.

Fig. 7.

a. Muscovite (M0) after biotite in F-trend paragneiss (sample BL92-47-213.2m; plane-polarized transmitted light). b. K0 kaolinite (K0) after biotite in F-trend paragneiss (sample BL92-41-122.4m; cross-polarized transmitted light). c. Hematite (F1) and euhedral Q1 quartz overgrowths mantle detrital Q0 quartz grains. Vivianite (P1a) fills primary porosity and is crosscut by K1 kaolinite. Late limonite stains all previous phases (sample BL06-65-116.3m; plane-polarized transmitted light). d. Fluorapatite (P1b) and M1 muscovite in sandstone interstices. The P1b fluorapatite displays hexagonal basal pinnacoid morphology. Both detrital Q0 quartz grains and P1b fluorapatite are partially dissolved in the presence of M1 muscovite (sample BL98-52-78.1m; SE-SEM image). e. Partially-dissolved P1b fluorapatite in contact with K1 kaolinite + M1 muscovite (sample BL98-52-78.1m; BSE-SEM image). f. Dolomite crosscuts P1b fluorapatite in F-trend basement paragneiss. Note extensively resorbed P1b grain boundaries (sample BL92-47-193.1m; cross-polarized transmitted light).

Fig. 7.

a. Muscovite (M0) after biotite in F-trend paragneiss (sample BL92-47-213.2m; plane-polarized transmitted light). b. K0 kaolinite (K0) after biotite in F-trend paragneiss (sample BL92-41-122.4m; cross-polarized transmitted light). c. Hematite (F1) and euhedral Q1 quartz overgrowths mantle detrital Q0 quartz grains. Vivianite (P1a) fills primary porosity and is crosscut by K1 kaolinite. Late limonite stains all previous phases (sample BL06-65-116.3m; plane-polarized transmitted light). d. Fluorapatite (P1b) and M1 muscovite in sandstone interstices. The P1b fluorapatite displays hexagonal basal pinnacoid morphology. Both detrital Q0 quartz grains and P1b fluorapatite are partially dissolved in the presence of M1 muscovite (sample BL98-52-78.1m; SE-SEM image). e. Partially-dissolved P1b fluorapatite in contact with K1 kaolinite + M1 muscovite (sample BL98-52-78.1m; BSE-SEM image). f. Dolomite crosscuts P1b fluorapatite in F-trend basement paragneiss. Note extensively resorbed P1b grain boundaries (sample BL92-47-193.1m; cross-polarized transmitted light).

Early diagenesis

A suite of minerals that formed during the early diagenesis of Thelon Formation sandstones is distinguished by its early paragenetic position and by its tendency to fill primary pore space.

Detrital quartz grains (Q0) are coated with a micrometer-thick layer of Fe-oxide (F1) (Fig. 7c). The F1 Fe-oxide rims are followed by quartz overgrowths (Q1) on Q0 detrital quartz. The Q1 overgrowths are generally poorly preserved, owing to resorption during peak diagenesis. Well-preserved examples of Q1 quartz (Fig. 7c) display similar paragenetic and morphological relationships to those recognized in the Athabasca and the eastern Thelon basins as compaction-related quartz cements (Hiatt et al., 2007, 2010).

Two varieties of early diagenetic phosphate minerals occur within sandstones of the Thelon Formation. Vivianite (P1a) (Fig. 7c) is sparsely distributed in sandstones along the F-trend and fills primary porosity. Fluorapatite (P1b) cement occurs in sandstones on both the F- and G-trends as zoned euhedral basal pinnacoids (Fig. 7d), 50 – 200 µm in diameter, which crosscut Q1 quartz overgrowths, and appear prismatic in thin section (Fig. 7e, f). It is most common in, but not restricted to, sandstones within 10 m of the unconformity and can completely fill primary and local secondary porosity. The distribution of P1b fluorapatite is similar to that described by Miller et al. (1989) as "strataform", and is not associated with veins or breccias in sandstones. Detrital phosphatic clasts, such as those observed in the eastern Thelon basin (Miller et al., 1989; Renac et al., 2002; Hiatt et al., 2010), were not observed. The P1b fluorapatite is also present in basement fractures and fault zones (Fig. 7f).

Fractures with anastomosing or "horsetail" morphology crosscut sandstones of the Thelon Formation throughout the study area and are healed by quartz (Q2). Pyrite (S1) is observed in sandstones and occurs as micron-scale veins and sooty black, dendritic aggregates of fine-grained euhedral cubes and pyritohedrons, generally in the basal 25 m of the Thelon Formation. The S1 pyrite crosscuts both P1b fluorapatite and Q2 quartz, and is, in turn, crosscut by peak diagenetic phyllosilicates (Fig. 8a).

Fracture-controlled dolomite (D1) is present in basement rocks only. The D1 dolomite is later than K0 kaolinite and P1b fluorapatite (Fig. 7f) and is, in turn, crosscut by peak diagenetic minerals. Based on these paragenetic relationships and its fracture-controlled nature, D1 dolomite is likely coeval with Q2 quartz-healed fractures in sandstones. The D1 dolomite is distinguished from D0 dolomite by its white to pink color and by its tendency to form continuous networks of cm-scale-wide veins. Chlorite (C1) is observed exclusively in basement rocks and is particularly prevalent along the F-trend. This phase weakly alters M0 muscovite and K0 kaolinite, and is crosscut by peak diagenetic M1 muscovite.

Peak diagenesis

Peak diagenetic minerals formed during deep burial of Thelon basin fill, and are distinguished in sandstones by their tendency to fill well-developed secondary porosity, and in the basement rocks by overprinting of K0 + M0 + C0 phyllosilicates.

Kaolinite (K1) is pervasive in sandstones of the Thelon Formation throughout the study area and fills secondary porosity. Morphology ranges from vermiform to very fine grained. The K0 kaolinite in basement rocks and K1 kaolinite in sandstones are partially to entirely replaced by muscovite (M1) (Fig. 8b). In sandstones, M1 muscovite is most abundant directly above the unconformity in secondary porosity developed at the expense of Q1 overgrowths and P1b fluorapatite (Fig. 7d, e). The M1 muscovite is followed by dickite (K2) formation in the sandstones. K2 dickite is distinguished from K1 kaolinite in all samples by SWIR spectrometry and XRD. Dickite-rich samples display equant blocky crystals that fill secondary porosity and are not overprinted by M1 muscovite (Fig. 8b), and are interpreted as K2 dickite pseudomorphs after K1 kaolinite. The K2 dickite is widely distributed in Sequence 3 sandstones, but is restricted to particular zones in Sequence 2 sandstones (Fig. 6).

In the basement rocks, M1 muscovite is most prevalent in the F-trend paragneiss and G-trend gneissic granitoids, and is distinguished from M0 muscovite by crosscutting relationships with P1b fluorapatite and by its finer grain size. The K2 dickite was not observed in basement rocks.

Hydrothermal alteration

A variety of Co + Ni + As + U- and other metal-bearing phases, phyllosilicates, and carbonate minerals are associated with intensely K0 + M1-altered paragneiss and brecciated graphitic schist in basement fault zones, and friable, intensely clay altered (K1 + M1 + K2) sandstones in the discovery zone.

Siderite and white mica, with a composition approaching aluminoceladonite, are the earliest hydrothermal phases. Siderite is prevalent in an approximately l-m-thick zone of intensely K0+M1-altered paragneiss, with high Co + Ni + As + Zn contents, and adjacent to graphitic breccia in a basement fault zone. Aluminoceladonite occurs as micrometer-wide veinlets in intensely clay-altered paragneiss immediately beneath the unconformity.

The U+4 phosphate mineral tristramite (P2) was observed in fractured, porous, P1b fluorapatite + S1 pyrite + M1 muscovite-altered sandstone. This phase follows P1b+S1+M1 paragenetically and is present as anhedral patches that are tens of microns in diameter and spatially associated with S1 pyrite (Fig. 8c, d). No uranium-bearing phases were observed in other discovery zone samples that were reported to have as much as ~500 ppm U by assay (Davidson and Gandhi, 1989; Davidson et al., 1998). A diverse suite of metal-bearing sulfides, selenides, arsenides, alloys, and rare native phases are collectively referred to as the S2 assemblage, and are associated with high U zones and intensely clay altered basement rocks and sandstones at the discovery zone (Table 1). Phases of the S2 assemblage are consistently associated with siderite in basement samples (Fig. 8e).

Sudoite (C2) (Fig. 8f) is prevalent in basal sandstones in the discovery zone, where it replaces M1 muscovite. The C2 sudoite is present in basal sandstones and shallow basement rocks as much as 2 km basinward from the discovery zone, and was observed in basal sandstones at the northeastern end of G-trend (Fig. 6).

Table 1.

Phases and Hosts of the S2 Assemblage

PhaseThelon Fmn. sandstoneBasement rocks
Unknown Co-Ni selenide
Unknown Co-As sulfide
Unknown Co-Ni arsenide
Ni-pyrite ("bravoite")
Unknown Ni-phosphide
Zn sulfide (sphalerite)
Unknown Cu-Zn
Cu sulfide (chalcopyrite)
Pb selenide ± Ag (clausthalite)
Pb sulfide (galena)
Unknown Bi selenide
Native Bi
PhaseThelon Fmn. sandstoneBasement rocks
Unknown Co-Ni selenide
Unknown Co-As sulfide
Unknown Co-Ni arsenide
Ni-pyrite ("bravoite")
Unknown Ni-phosphide
Zn sulfide (sphalerite)
Unknown Cu-Zn
Cu sulfide (chalcopyrite)
Pb selenide ± Ag (clausthalite)
Pb sulfide (galena)
Unknown Bi selenide
Native Bi
Fig. 8.

a. Fluorapatite (P1b) crosscuts Q1 quartz overgrowths and is, in turn, crosscut by S1 pyrite. K1 kaolinite crosscuts S1 pyrite (sample BL07-70-210.8m; BSE-SEM image). b. Fine-grained K1 kaolinite is partially replaced by M1 muscovite. Coarser K2 dickite in the right half of the image is not replaced by M1 muscovite (sample JP-1-114.6m; cross-polarized transmitted light). c. and d. Tristramite (P2) in P1b fluorapatite + S1 pyrite + M1 muscovite-altered F-trend sandstone at the discovery zone. The P1b grain boundaries are extensively resorbed and in contact with M1 muscovite. The P2 tristramite is coincident with areas of increased S1 pyrite concentration (sample BL83-21-98.9m; BSE-SEM image). e. Hydrothermal siderite and Co + Ni arsenide in F-trend basement at the discovery zone (sample BL98-52-87.0m; BSE-SEM image). f. C2 sudoite replaces M1 muscovite in F-trend sandstone at the discovery zone (sample BL98-52-82.2m; BSE-SEM image).

Fig. 8.

a. Fluorapatite (P1b) crosscuts Q1 quartz overgrowths and is, in turn, crosscut by S1 pyrite. K1 kaolinite crosscuts S1 pyrite (sample BL07-70-210.8m; BSE-SEM image). b. Fine-grained K1 kaolinite is partially replaced by M1 muscovite. Coarser K2 dickite in the right half of the image is not replaced by M1 muscovite (sample JP-1-114.6m; cross-polarized transmitted light). c. and d. Tristramite (P2) in P1b fluorapatite + S1 pyrite + M1 muscovite-altered F-trend sandstone at the discovery zone. The P1b grain boundaries are extensively resorbed and in contact with M1 muscovite. The P2 tristramite is coincident with areas of increased S1 pyrite concentration (sample BL83-21-98.9m; BSE-SEM image). e. Hydrothermal siderite and Co + Ni arsenide in F-trend basement at the discovery zone (sample BL98-52-87.0m; BSE-SEM image). f. C2 sudoite replaces M1 muscovite in F-trend sandstone at the discovery zone (sample BL98-52-82.2m; BSE-SEM image).

Mineral Chemistry

Retrograde metamorphism and pre-Thelon basin weathering

Typical M0 muscovite in basement rocks contains the highest K2O content of all Boomerang Lake white mica analyzed (Fig. 9; Table 2). The M0 muscovite also has higher MgO and FeO than other Boomerang Lake white mica (3.3 and 2.6 wt %, respectively), which may have been inherited from biotite. The estimated temperature of formation of M0 muscovite is 290°C (Fig. 5).

The C0 chlorite has lower Mg contents (11.4 wt % MgO) and higher Al2O3 and FeO contents (18.0 and 30.3 wt %, respectively) than C1 chlorite (Fig. 10; Table 2). The calculated temperature of formation of C0 chlorite is 340°C, although this is a minimum temperature because it is 30°C beyond the calibrated range of the geothermometer. We estimate a minimum temperature of about 300°C for the assemblage C0 chlorite + M0 muscovite, which probably has a retrograde metamorphic origin based on its relatively high temperatures of formation, coarse grain size, and replacement of prograde metamorphic biotite.

Fig. 9.

Relationship between K and the degree of substitution for octahedral Al in white mica at Boomerang Lake, in reference to typical compositions of muscovite, illite, and aluminoceladonite reported by Deer et al. (1992). apfu = atoms per formula unit.

Fig. 9.

Relationship between K and the degree of substitution for octahedral Al in white mica at Boomerang Lake, in reference to typical compositions of muscovite, illite, and aluminoceladonite reported by Deer et al. (1992). apfu = atoms per formula unit.

The I0 illite occupying fault zones in F-trend basement rocks, including the Boomerang Lake discovery zone, is characterized by a notable interlayer site deficiency (8.8 wt % K2O; Table 2), and higher MgO and FeO contents (3.0 and 2.8 wt percent, respectively) than M1 muscovite (Fig. 9). These compositions, as well as SiO2 and Al2O3 contents of 52.7 and 26.8 wt percent, respectively, are consistent with that of typical illite (Fig. 9) (Deer et al., 1992). The I0 illite has a Kübler Index of 0.95, which is 0.3 to 0.5 °2θ higher relative to those of M1 muscovite (Table 3), suggesting a lower temperature of formation (Árkai, 1991).

Two samples of K0 kaolinite display Hinckley indices of 0.6 (Table 3), which is similar to those reported by Zhang et al. (2001) from kaolinite sampled in basement "paleoregolith" in the Athabasca basin. The apparent temporal relationship between I0 illite and K0 kaolinite + F0 hematite + D0 dolomite, and the association of these minerals with paleosol formation (Gall, 1994), are used to infer an original formation temperature of about 50°C for this mineral assemblage. However, the calculated temperature of formation of I0 illite, based on EMPA-derived site occupancy data, is approximately 200°C (Fig. 5; Table 2). Thus, although the I0 illite experienced higher temperatures after formation, the original poorly ordered structure was not modified. Five samples of K0 kaolinite have Hinckley indices of 1.1 to 1.2 (Table 3), which are similar to those from sandstone- and basement-hosted kaolinite in alteration halos associated with U mineralization in the Athabasca basin (Zhang et al., 2001). These samples likely reached 200°C, based on calculated I0 illite temperatures, but under conditions in which the original poorly ordered structure was modified to a more ordered state. It is possible that basement rocks reached temperatures of about 200°C during subsidence associated with the deep burial of Thelon basin fill.

Fig. 10.

Ternary diagram showing the chemical variation of chlorites at Boomerang Lake, in reference to the composition of relatively unaltered biotite in F-trend paragneiss at Boomerang Lake as determined by EMPA, typical compositions of chamosite and clinochlore reported by Deer et al. (1992), and sudoite reported by Lin and Bailey (1985).

Fig. 10.

Ternary diagram showing the chemical variation of chlorites at Boomerang Lake, in reference to the composition of relatively unaltered biotite in F-trend paragneiss at Boomerang Lake as determined by EMPA, typical compositions of chamosite and clinochlore reported by Deer et al. (1992), and sudoite reported by Lin and Bailey (1985).

Table 2.

Representative Electron Microprobe Analyses of Phyllosilicates at Boomerang Lake

Sample123456789
Oxide (wt %)
SiO245.7652.6748.7247.2747.1858.4826.8732.0036.06
A2O332.4826.7633.7833.7617.7413.7217.9620.4832.43
FeO2.572.840.760.407.714.6030.3018.703.28
MnO0.030.02<DL0.020.070.020.06<DL<DL
MgO3.303.041.361.252.227.6711.4413.1014.51
TiO20.350.16<DL<DL0.02<DL0.130.04<DL
Cr2O3<DL<DL0.02<DL2.83<DL<DL0.020.04
V2O3n.a.n.a.0.02<DL2.10<DL0.05n.a.n.a.
BaOn.a.n.a.<DL0.130.12<DL<DLn.a.n.a.
CaO0.020.340.120.080.45<DL0.040.160.07
Na2O0.140.070.040.260.05<DL0.020.060.00
10.498.799.4210.334.0010.140.110.840.26
Cl0.020.05<DL<DL2.220.020.030.06<DL
F<DL0.540.40<DL0.200.400.040.11n.a.
O=Cl0.000.010.000.000.500.000.010.010.00
o=f0.000.230.170.000.080.170.020.040.00
TOTAL95.1795.0694.4893.4886.3394.9287.0285.5186.68
Atomic proportions
Number of oxygens222222222222282828
Tetrahedral Sites
Si6.026.416.346.305.806.394.766.576.55
AlIV1.981.591.661.702.201.613.241.431.45
Sum8.008.008.008.008.008.008.008.008.00
Octahedral sites
AlVI3.393.393.673.752.832.864.003.535.49
Fe0.280.290.080.040.790.424.493.210.50
Mn0.000.000.000.000.010.000.010.000.00
Mg0.650.550.260.250.411.253.024.013.93
Ti0.030.020.000.000.000.000.020.010.00
Sum4.354.254.014.044.044.5311.5410.769.92
Interlayer site
Ca0.000.040.020.010.060.000.010.040.01
Na0.040.020.010.070.010.000.010.020.00
K1.761.361.571.760.631.410.020.220.06
Sum1.801.421.601.840.701.410.040.280.07
Anions
Cl0.000.010.000.000.460.000.010.020.00
F0.000.210.170.000.080.140.020.070.00
OH4.003.783.834.003.463.8615.9715.9116.00
Temp. (°C)290210240260n.a.220340160190
Sample123456789
Oxide (wt %)
SiO245.7652.6748.7247.2747.1858.4826.8732.0036.06
A2O332.4826.7633.7833.7617.7413.7217.9620.4832.43
FeO2.572.840.760.407.714.6030.3018.703.28
MnO0.030.02<DL0.020.070.020.06<DL<DL
MgO3.303.041.361.252.227.6711.4413.1014.51
TiO20.350.16<DL<DL0.02<DL0.130.04<DL
Cr2O3<DL<DL0.02<DL2.83<DL<DL0.020.04
V2O3n.a.n.a.0.02<DL2.10<DL0.05n.a.n.a.
BaOn.a.n.a.<DL0.130.12<DL<DLn.a.n.a.
CaO0.020.340.120.080.45<DL0.040.160.07
Na2O0.140.070.040.260.05<DL0.020.060.00
10.498.799.4210.334.0010.140.110.840.26
Cl0.020.05<DL<DL2.220.020.030.06<DL
F<DL0.540.40<DL0.200.400.040.11n.a.
O=Cl0.000.010.000.000.500.000.010.010.00
o=f0.000.230.170.000.080.170.020.040.00
TOTAL95.1795.0694.4893.4886.3394.9287.0285.5186.68
Atomic proportions
Number of oxygens222222222222282828
Tetrahedral Sites
Si6.026.416.346.305.806.394.766.576.55
AlIV1.981.591.661.702.201.613.241.431.45
Sum8.008.008.008.008.008.008.008.008.00
Octahedral sites
AlVI3.393.393.673.752.832.864.003.535.49
Fe0.280.290.080.040.790.424.493.210.50
Mn0.000.000.000.000.010.000.010.000.00
Mg0.650.550.260.250.411.253.024.013.93
Ti0.030.020.000.000.000.000.020.010.00
Sum4.354.254.014.044.044.5311.5410.769.92
Interlayer site
Ca0.000.040.020.010.060.000.010.040.01
Na0.040.020.010.070.010.000.010.020.00
K1.761.361.571.760.631.410.020.220.06
Sum1.801.421.601.840.701.410.040.280.07
Anions
Cl0.000.010.000.000.460.000.010.020.00
F0.000.210.170.000.080.140.020.070.00
OH4.003.783.834.003.463.8615.9715.9116.00
Temp. (°C)290210240260n.a.220340160190

Notes: Phyllosilicate minerals with drill hole name and depth in parenthesis: 1 = M0 muscovite (BL06-65-240.2m), 2 = I0 illite (BL06-65-170.0m), 3 = M1 muscovite, Thelon Fmn.-sandstone-hosted (JP-2-231.2m); 4 = M1 muscovite, basement-rock-hosted (BL92-47-193.1m), 5 = M1 muscovite, Thelon Fmn.-sandstone-hosted, altered (BL83-21-98.9m), 6 = "aluminoceladonite" (BL98-52-84.0m), 7 = C0 chlorite (BL98-56-160.0m), 8 = C1 chlorite (BL92-47-193.1m), 9 = C2 sudoite (BL98-52-90.7m); atomic proportions calculated on an anhydrous basis, n.a. = not analyzed, <DL = below detection limit, OH calculated by subtraction; temperatures were calculated using the methods of Cathelineau (1988) and Zang and Fyfe (1995)

Early diagenesis

The P1b fluorapatite in the F- and G-trend sandstones is nearly stoichiometric, with 42.0 wt percent P2O5, 55.7 wt percent CaO, and about 4 wt percent F (Table 4). Trace element concentrations, including those for LREE, S, Sr, Y, and Ba, are very low, and uranium contents were below the analytical detection limit. Thus, P1b fluorapatite at Boomerang Lake is distinct from early diagenetic fluorapatite in the eastern Thelon basin that contains several thousands of ppm U (Miller et al., 1989; Hiatt et al., 2010).

Table 3.

Kübler and Hinckley Indices of Phyllosilicates

Kübler Index (Kübler, 1967)
SampleMineralSize fractionHost rockKübler index
BL98-52-78.1mM1 muscovite<2Thelon Fmn. sandstone, discovery zone0.61
JP-2-219.6mM1 muscovite<2Thelon Fmn. sandstone0.66
JP-2-231.2mM1 muscovite<2Thelon Fmn. sandstone0.50
BL06-65-142.8mM1 muscovite<2 μmThelon Fmn. sandstone, near unconformity0.60
BL07-70-370.4mM1 muscovite<2Thelon Fmn. sandstone, near unconformity0.58
BL06-60-243.0mM1 muscovite<2Basement rocks, near unconformity0.27
BL06-65-222.4mM1 muscovite<2Basement rocks0.39
BL06-65-170.0m10 illite<2Basement rocks, fault zone0.95
Hinckley Index (Hinckley, 1963)
SampleMineralSize fractionHost rockHinckley index
BL07-69-55.0mK1 kaolinite<2 μmThelon Fmn. sandstone1.6
BL98-52-66.5mK1 kaolinite5-10Thelon Fmn. sandstone, discovery zone1.6
BL06-62-88.4mK1 kaolinite2-5Thelon Fmn. sandstone1.5
BL92-41-93.3mK0 kaolinitemBasement rocks1.1
BL06-64-99.2mK0 kaolinite2-5 μmBasement rocks1.2
BL83-22-114.0mK0 kaolinitemBasement rocks0.6
BL92-43-205.8mK0 kaolinitemBasement rocks0.6
BL07-69-272.9mK0 kaolinite2-5Basement rocks1.1
BL07-68-451.8mK0 kaolinitemBasement rocks, vein1.2
Kübler Index (Kübler, 1967)
SampleMineralSize fractionHost rockKübler index
BL98-52-78.1mM1 muscovite<2Thelon Fmn. sandstone, discovery zone0.61
JP-2-219.6mM1 muscovite<2Thelon Fmn. sandstone0.66
JP-2-231.2mM1 muscovite<2Thelon Fmn. sandstone0.50
BL06-65-142.8mM1 muscovite<2 μmThelon Fmn. sandstone, near unconformity0.60
BL07-70-370.4mM1 muscovite<2Thelon Fmn. sandstone, near unconformity0.58
BL06-60-243.0mM1 muscovite<2Basement rocks, near unconformity0.27
BL06-65-222.4mM1 muscovite<2Basement rocks0.39
BL06-65-170.0m10 illite<2Basement rocks, fault zone0.95
Hinckley Index (Hinckley, 1963)
SampleMineralSize fractionHost rockHinckley index
BL07-69-55.0mK1 kaolinite<2 μmThelon Fmn. sandstone1.6
BL98-52-66.5mK1 kaolinite5-10Thelon Fmn. sandstone, discovery zone1.6
BL06-62-88.4mK1 kaolinite2-5Thelon Fmn. sandstone1.5
BL92-41-93.3mK0 kaolinitemBasement rocks1.1
BL06-64-99.2mK0 kaolinite2-5 μmBasement rocks1.2
BL83-22-114.0mK0 kaolinitemBasement rocks0.6
BL92-43-205.8mK0 kaolinitemBasement rocks0.6
BL07-69-272.9mK0 kaolinite2-5Basement rocks1.1
BL07-68-451.8mK0 kaolinitemBasement rocks, vein1.2

Notes: m = mineral was sampled by microdrill

The C1 chlorite in basement rocks has higher MgO contents of 13.1 wt percent, and lower FeO contents of 18.7 wt percent (Fig. 10; Table 2) than C0 chlorite. The K2O contents of as much as 1.3 wt percent suggest small-scale intergrowth with remnant M0 muscovite in C1 chlorite. The estimated temperature of formation of C1 chlorite ranges from 160° to 220°C.

Peak diagenesis

The M1 muscovite in basement rocks contains lower MgO and FeO contents of 1.2 and 0.4 wt percent, respectively, than M0 muscovite (Fig. 9; Table 2). The estimated temperature of formation of M1 muscovite in sandstones and basement rocks is 250°C. The M1 muscovite associated with the U-bearing tristramite (P2) in the discovery zone contains significantly less K2O and Al2O3 (4.0 and 17.7 wt %, respectively) than typical M1 muscovite (Fig. 9; Table 2), and also contains approximately 10 wt percent combined MgO and FeO, 5 wt percent combined Cr2O3 and V2O3, and as much as 4.8 wt percent Cl.

Hydrothermal alteration

Scanning electron microscopy and EMPA reveal that the U-bearing phase (P2) in the discovery zone is the rare U+4 phosphate mineral tristramite. This is contrary to the findings of Davidson and Gandhi (1989), who described uranium mineralization in the same thin section as fine-grained pitchblende. Analyses of P2 tristramite from Boomerang Lake are similar to those reported by Atkin et al. (1983), with 13.7 wt percent CaO, 25.6 wt percent P2O5, and 35.2 wt percent UO2 (Table 4). Davidson and Gandhi (1989) acknowledge an association of U with P and Ca, but attribute it to the influence of apatite (P1b fluorapatite of this study). However, we observed the U-bearing phase to be in direct contact with S1 pyrite or M1 muscovite in nearly all cases (Fig. 8c, d).

The P2 tristramite analyses show as much as 5 and 9 wt percent FeO and SO3, respectively. The highest FeO and SO3 values were obtained in portions of tristramite that contained micrometer-sized inclusions. Although the inclusions are too small to analyze, EDS spectra showed that the inclusions contained a high concentration of Fe and S, and may represent remnant S1 pyrite. The lowest FeO and SO3 contents (1 and 2 wt percent, respectively) were obtained in portions of tristramite that contained no inclusions.

Hydrothermal aluminoceladonite contains low Al2O3 (13.7 wt percent) due to substantial substitution of AlIV by SiO2 (58.5 wt %), and substitution of AlVI by MgO and FeO, (7.7 and 4.6 wt %, respectively). This high degree of Al substitution distinguishes aluminoceladonite from all other white micas at Boomerang Lake (Fig. 9; Table 2). The estimated temperature of formation of aluminoceladonite is 220°C (Fig. 5).

The C2 sudoite is distinct from C0 and C1 chlorites, having the lowest FeO contents (3.3 wt %) and the highest Al2O3 content (32.4 wt %) (Fig. 10; Table 2). The C2 sudoite analyses show low amounts of K2O, typically 0.3 wt percent, which probably indicates small-scale intergrowth with remnant M1 muscovite that it partially replaces. The estimated temperature of formation of C2 sudoite is 190°C.

Stable Isotope Geochemistry

Pre-Thelon basin weathering

The K0 kaolinite and I0 illite from the F– and G-trend basement rocks have δ18O values that range from 9.3 to 15.7 per mil, and δ2H values that range from –69 to –55 per mil (Table 5). Assuming a temperature of formation of 50°C for I0 illite and the two samples of K0 kaolinite with the lowest Hinckley indices, the calculated δ18Ofluid and δ2Hfluid values range from –6.7 to –3.8 per mil and –35 to –28 per mil (Fig. 11a), respectively. A temperature of 200°C, which was the temperature reached during basement subsidence, is used to calculate δ18Ofluid values between 7.7 and 10.1‰ and δ2Hfluid values between –52 and –37‰ for the K0 kaolinite having higher Hinckley indices (Fig. 11a).

Table 4.

Representative Electron Microprobe Analyses of Phosphates At Boomerang Lake

Sample12
Oxide (wt %)
SrO0.060.82
CaO55.6913.74
Na2O<DL0.08
BaO<DL1.45
Y2O30.052.74
La2O30.040.12
Ce2O3<DL0.91
Pr2O3n.a.n.a.
Nd2O3<DL0.42
Sm2O30.060.17
UO2<DL35.18
ThO2n.a.n.a.
PbO2n.a.0.12
SiO2<DL0.13
Al2O3n.a.n.a.
FeO<DL2.36
MnO0.020.19
P2O541.9725.63
SO30.024.88
SeO4n.a.1.13
Cl0.020.07
F3.620.19
O=Cl0.000.02
O=F1.520.08
Total100.0189.11
Atomic proportions
number of oxygens124
Sr0.000.02
Ca4.640.57
ΣLREE0.000.02
Un.a.0.30
Thn.a.n.a.
Aln.a.n.a.
Fe0.000.08
P2.760.85
S0.000.14
F0.890.02
OH0.11*1.35
Sample12
Oxide (wt %)
SrO0.060.82
CaO55.6913.74
Na2O<DL0.08
BaO<DL1.45
Y2O30.052.74
La2O30.040.12
Ce2O3<DL0.91
Pr2O3n.a.n.a.
Nd2O3<DL0.42
Sm2O30.060.17
UO2<DL35.18
ThO2n.a.n.a.
PbO2n.a.0.12
SiO2<DL0.13
Al2O3n.a.n.a.
FeO<DL2.36
MnO0.020.19
P2O541.9725.63
SO30.024.88
SeO4n.a.1.13
Cl0.020.07
F3.620.19
O=Cl0.000.02
O=F1.520.08
Total100.0189.11
Atomic proportions
number of oxygens124
Sr0.000.02
Ca4.640.57
ΣLREE0.000.02
Un.a.0.30
Thn.a.n.a.
Aln.a.n.a.
Fe0.000.08
P2.760.85
S0.000.14
F0.890.02
OH0.11*1.35

Notes: Phosphate minerals with drill hole name and depth in parenthesis: 1 = P1b fluorapatite (BL07-70-210.8m); 2 = P2 tristramite (BL83-21-98.9m); atomic proportions calculated on an anhydrous basis; <DL = below detection limit; n.a. = not analyzed; * = expressed as H2O; OH and H2O calculated by subtraction

Early diagenesis

The D1 dolomite from F-trend basement-hosted veins has δ18O values that range from 20.2 to 25.0 per mil, and δ13C values that vary from –10.6 to –4.7 per mil (Table 5). A minimum temperature of 130°C for early diagenesis is inferred from the petrography, fluid inclusion microthermometry, and stable isotope geochemistry of early diagenetic quartz overgrowths in the eastern Thelon basin (Renac et al., 2002; Hiatt et al., 2007, 2010). Assuming that temperatures during early diagenesis in the western Thelon basin were similar, the δ18O values of fluids in equilibrium with D1 dolomite were between 5.1 and 9.9 per mil (Fig. 11b).

Peak diagenesis

The K1 kaolinite, M1 muscovite, and K2 dickite occupying secondary porosity in Thelon Formation sandstones on the Fand G-trends have δ18O values that range from 10.0 to 15.0 per mil, and have δ2H values that fall between –92 and –47 per mil (Table 5). Temperatures between 200° and 250°C, based on tetrahedral site occupancy of M1 muscovite, were used to calculate δ18Ofluid values between 6.7 and 9.4 per mil, and δ2Hfluid values between –76 and –24 per mil (Fig. 11a). The K2 dickite samples occupying fractures and vugs in sandstone have δ18Ofluid values that are approximately 3 per mil lower than interstitial K2 dickite (Fig. 11a). Samples of K2 dickite from outcrop have the lowest δ2Hfluid values that range from –76 to –56 per mil (Fig. 11a).

Hydrothermal alteration

The C2 sudoite from Thelon Formation sandstones have δ18O values between 10.3 and 12.5 per mil and have δ2H values that range from –59 to –52 per mil (Table 5). At a temperature of 200°C, the fluids in equilibrium with C2 sudoite had δ18Ofluid values between 8.0 and 10.2 per mil, and δ18Hfluid values between –25 and –18 per mil (Fig. 11a). One sample of hydrothermal siderite has a similar high-δ18Ofluid value of 11.1 per mil, and a δ13Cmineral value of –14.5 per mil (Table 5; Fig. 11b).

The range of δ18Ofluid values associated with regionally occurring kaolinite and dickite in Athabasca sandstones is similar to that of K1 kaolinite and K2 dickite at Boomerang Lake (Fig. 11a). However, the majority of δ18Ofluid values associated with muscovite/illite and sudoite in alteration halos in the Athabasca basin are generally 3 to 5 – lower than δ18Ofluid values associated with M1 muscovite and C2 sudoite at Boomerang Lake (Fig. 11a). This suggests comparatively lower water/rock ratios during peak diagenesis and hydrothermal alteration at Boomerang Lake.

40Ar/39Ar Geochronology

Basement-hosted I0 illite and M1 muscovite, and sandstone-hosted M1 muscovite were dated by the 40Ar/39Ar method (Table 6). The age spectrum of one I0 illite sample from an F-trend basement fault zone displays a slightly disturbed profile and yields a pseudo-plateau age of 1758 ± 7 Ma (Fig. 12). Duplicate analyses of M1 muscovite after M0 muscovite give plateau ages of 1752 ± 19 and 1738 ± 14 Ma. These ages are consistent with the age of late retrograde metamorphism or basement weathering and paleosol formation, and indicate that the Ar isotopic system in these samples was not disturbed during Thelon basin formation and diagenesis.

Table 5.

Oxygen, Hydrogen, and Carbon Stable Isotope Compositions of Alteration Phyllosilicates and Carbonates at Boomerang Lake

SampleLithologyMineralFraction sizeδ18OminδDminδ13CminH2O (%)Temp (°C)δ18OfluidδDfluid
Pre-Thelon basement paleosol
BL07-67-60.0mbsK0 kaolinite<2 μm9.3-608.92007.7-42
BL06-64-99.2mbsK0 kaolinite2-59.6-658.02008.0-48
BL07-69-272.9mbsK0 kaolinite2-511.8-6510.32008.2-47
BL07-68-451.8mbsK0 kaolinitem15.7-5516.120010.1-37
BL92-41-93.3mbsK0 kaolinitem14.6-6914.62009.0-52
BL83-22-114.0mbsK0 kaolinitem15.3-6413.9<50-4.4-35
BL92-43-205.8mbsK0 kaolinitem13.0-5712.2<50-6.7-28
BL06-65-170.0mbs10 illite<215.2-656.1<50-3.8-31
BL06-65-162.8mbsD0 dolomitem25.4-3<50-2.9
BL06-65-165.8mbsD0 dolomitem25.3-2.9<50-3.0
Peak diagenetic minerals
BL92-45-152.2mbsD1 dolomitem20.2-4.71305.1
BL92-47-193.1mbsD1 dolomitem25.0-10.61309.9
BL06-65-171.4mbsD1 dolomitem23.6-8.41308.4
BL07-69-55.0mssK1 kaolinite<214.4-6215.12008.8-44
BL06-62-88.4mssK1 kaolinite2-5 μm15.0-6113.12009.4-43
BL98-52-66.5mssK1 kaolinite5-1014.8-5614.32009.3-38
JP-2-219.6mssM1 muscovite<213.4-596.32508.6-25
JP-2-231.2mssM1 muscovite<213.2-636.02508.4-29
BL07-70-370.0mssM1 muscovite<212.4-586.62507.6-24
BL98-52-78.1mssM1 muscovite<2 μm13.8-646.02508.9-30
BL06-65-142.8mssM1 muscovite<212.5-677.12507.7-33
BL07-69-74.9mssK2 dickite5-1010.0-5313.92506.7-37
BL07-69-84.8mssK2 dickite5-10 μm11.3-5813.42508.0-43
BL07-68-198.1mssK2 dickite5-1011.2-4713.52507.9-31
BL91-35-77.9mssK2 dickite5-10 μm10.4-6010.92507.0-45
BL92-50-130.3mssK2 dickite5-1010.2-5411.32506.8-38
Th08-1ssK2 dickite2-512.6-9210.42509.2-76
Th08-6ssK2 dickite2-5 μm12.2-8211.02508.9-67
Th08-8ssK2 dickite2-511.6-7211.52508.2-56
BL07-67-53.4mssK2 dickitem8.2-5215.82504.8-36
BL07-70-130.3mssK2 dickitem7.6-5215.62504.3-36
BL07-69-240.3mssK2 dickitem8.9-5414.62505.6-39
BL07-69.264.2mssK2 dickitem7.7-5015.02504.4-35
Hydrothermalalteration
BL98-52-87.0mbssideritem22.1-14.520011.1
JP-1-260.5mssC2 sudoite<2 μm11.8-5910.22009.6-25
JP-4-209.0mssC2 sudoite<211.4-5611.22009.1-22
JP-4-232.6mssC2 sudoite<211.6-5410.32009.3-20
JP-4-255.5mssC2 sudoite<210.3-5212.22008.0-18
BL07-70-378.9mssC2 sudoite<211.3-5612.72009.0-22
BL83-22-93.3mssC2 sudoite<2 μm12.5-5911.020010.2-25
BL06-61-190.7mssC2 sudoite<211.6-5511.92009.3-21
SampleLithologyMineralFraction sizeδ18OminδDminδ13CminH2O (%)Temp (°C)δ18OfluidδDfluid
Pre-Thelon basement paleosol
BL07-67-60.0mbsK0 kaolinite<2 μm9.3-608.92007.7-42
BL06-64-99.2mbsK0 kaolinite2-59.6-658.02008.0-48
BL07-69-272.9mbsK0 kaolinite2-511.8-6510.32008.2-47
BL07-68-451.8mbsK0 kaolinitem15.7-5516.120010.1-37
BL92-41-93.3mbsK0 kaolinitem14.6-6914.62009.0-52
BL83-22-114.0mbsK0 kaolinitem15.3-6413.9<50-4.4-35
BL92-43-205.8mbsK0 kaolinitem13.0-5712.2<50-6.7-28
BL06-65-170.0mbs10 illite<215.2-656.1<50-3.8-31
BL06-65-162.8mbsD0 dolomitem25.4-3<50-2.9
BL06-65-165.8mbsD0 dolomitem25.3-2.9<50-3.0
Peak diagenetic minerals
BL92-45-152.2mbsD1 dolomitem20.2-4.71305.1
BL92-47-193.1mbsD1 dolomitem25.0-10.61309.9
BL06-65-171.4mbsD1 dolomitem23.6-8.41308.4
BL07-69-55.0mssK1 kaolinite<214.4-6215.12008.8-44
BL06-62-88.4mssK1 kaolinite2-5 μm15.0-6113.12009.4-43
BL98-52-66.5mssK1 kaolinite5-1014.8-5614.32009.3-38
JP-2-219.6mssM1 muscovite<213.4-596.32508.6-25
JP-2-231.2mssM1 muscovite<213.2-636.02508.4-29
BL07-70-370.0mssM1 muscovite<212.4-586.62507.6-24
BL98-52-78.1mssM1 muscovite<2 μm13.8-646.02508.9-30
BL06-65-142.8mssM1 muscovite<212.5-677.12507.7-33
BL07-69-74.9mssK2 dickite5-1010.0-5313.92506.7-37
BL07-69-84.8mssK2 dickite5-10 μm11.3-5813.42508.0-43
BL07-68-198.1mssK2 dickite5-1011.2-4713.52507.9-31
BL91-35-77.9mssK2 dickite5-10 μm10.4-6010.92507.0-45
BL92-50-130.3mssK2 dickite5-1010.2-5411.32506.8-38
Th08-1ssK2 dickite2-512.6-9210.42509.2-76
Th08-6ssK2 dickite2-5 μm12.2-8211.02508.9-67
Th08-8ssK2 dickite2-511.6-7211.52508.2-56
BL07-67-53.4mssK2 dickitem8.2-5215.82504.8-36
BL07-70-130.3mssK2 dickitem7.6-5215.62504.3-36
BL07-69-240.3mssK2 dickitem8.9-5414.62505.6-39
BL07-69.264.2mssK2 dickitem7.7-5015.02504.4-35
Hydrothermalalteration
BL98-52-87.0mbssideritem22.1-14.520011.1
JP-1-260.5mssC2 sudoite<2 μm11.8-5910.22009.6-25
JP-4-209.0mssC2 sudoite<211.4-5611.22009.1-22
JP-4-232.6mssC2 sudoite<211.6-5410.32009.3-20
JP-4-255.5mssC2 sudoite<210.3-5212.22008.0-18
BL07-70-378.9mssC2 sudoite<211.3-5612.72009.0-22
BL83-22-93.3mssC2 sudoite<2 μm12.5-5911.020010.2-25
BL06-61-190.7mssC2 sudoite<211.6-5511.92009.3-21

Notes: Temperatures of white mica and chlorite were calculated using mineral chemistry and the methods of Cathelineau (1988) and Zang and Fyfe (1995); temperatures used for kaolin and carbonate minerals are discussed in the text; bs = basement rocks; ss = Thelon Formation sandstone; m = sampled by microdrill; oxygen and hydrogen isotope ratios are in units of per mil relative to V-SMOW; carbon isotope ratios are in units of per mil relative to PDB

The M1 muscovite, sampled from sandstone of the Thelon Formation located to the northeast of the Eyeberry inlier, displays a relatively undisturbed age spectra with a plateau age of 1339 ± 6 Ma (Fig. 12). The M1 muscovite sampled from sandstone within 1 m above the unconformity on the F-trend also displays a relatively undisturbed age spectrum that gives the same age of 1337 ± 4 Ma. The M1 muscovite sampled from sandstone within the discovery zone displays a disturbed age spectra with a pseudo-plateau age of 1302 ± 11 Ma. Ages of M1 muscovite in sandstones are ca. 400 m.y. younger than those in basement rocks, and indicate that the Ar isotope system in these samples was open until long after Thelon basin formation and diagenesis.

U-Pb Isotope and Trace Element Geochemistry

Radiogenic and highly radiogenic Pb is observed in both sandstones of the Thelon Formation and basement rocks on the F- and G-trends (Fig. 13, Table 7). The 207Pb/206Pb ratios ranging from 0.6 to 0.9 are referred to as weakly radiogenic because these values reflect a significant contribution from modern common Pb. The 207Pb/206Pb ratios ranging from 0.3 to 0.6 are termed radiogenic here, because they reflect an increasing proportion of radiogenic Pb that was sourced from the decay of U in a possible nearby Proterozoic U deposit. The 207Pb/206Pb ratios ranging from 0.1 to 0.3 are highly radiogenic and reflect a high proportion of radiogenic, Proterozoic Pb that would be expected from a U deposit of this eon. Excess radiogenic Pb that cannot be accounted for by the decay of U contained in a sample is referred to as unsupported radiogenic Pb, whereas radiogenic Pb that can be accounted for by the decay of U contained in a sample is referred to as supported radiogenic Pb (Holk et al., 2003).

Fig. 11.

a. Calculated (δ18O and (δ2H values of fluids in equilibrium with minerals at Boomerang Lake. Fields defining the range of calculated (δ18O and (δ2H values of fluids in equilibrium with sandstone-hosted kaolinite and dickite (a) and muscovite/illite and sudoite (b) in the Athabasca basin are plotted in gray for reference (MWL = meteoric water line, V-SMOW = Vienna Standard Mean Ocean Water). Sources of Athabasca data are Wilson and Kyser (1987), Kotzer (1993), Kotzer and Kyser (1995), Wasyliuk (2001), Alexandre et al. (2005), Cloutier (2009), and Cloutier et al. (2009). Athabasca δ18Ofluid and (δ18Hfluid values were calculated using temperatures suggested by the data authors, and fractionation factors presented in this paper for consistency. b. Plot of δ18Ofluid versus (δ13Cmineral compositions of carbonate minerals.

Fig. 11.

a. Calculated (δ18O and (δ2H values of fluids in equilibrium with minerals at Boomerang Lake. Fields defining the range of calculated (δ18O and (δ2H values of fluids in equilibrium with sandstone-hosted kaolinite and dickite (a) and muscovite/illite and sudoite (b) in the Athabasca basin are plotted in gray for reference (MWL = meteoric water line, V-SMOW = Vienna Standard Mean Ocean Water). Sources of Athabasca data are Wilson and Kyser (1987), Kotzer (1993), Kotzer and Kyser (1995), Wasyliuk (2001), Alexandre et al. (2005), Cloutier (2009), and Cloutier et al. (2009). Athabasca δ18Ofluid and (δ18Hfluid values were calculated using temperatures suggested by the data authors, and fractionation factors presented in this paper for consistency. b. Plot of δ18Ofluid versus (δ13Cmineral compositions of carbonate minerals.

In sandstones from the F-trend, radiogenic Pb is restricted to within several meters of the unconformity, but occurs in stratigraphically higher zones in sandstones along the G-trend. The F-trend basement rocks are generally more radiogenic than G-trend basement rocks, due in part to contrasting lithologies, and they display 207Pb/206Pb ratios of about 0.55. Sandstones and basement rocks in the discovery zone are weakly radiogenic to radiogenic (Table 7).

All samples have high 238U/206Pb ratios that are indicative of Pb produced in situ or from a young uranium source. Specific samples in the discovery zone are marked by very high 238U/206Pb ratios ranging from 156 to 317 (Fig. 14).

The 206Pb/204Pb ratios versus 207Pb/204Pb ratios for all samples are displayed in Figure 15. A high proportion of the data extend off the Pb growth curve of Stacey and Kramers (1975) and forms two distinct Pb-mixing isochrons. The majority of the sampled sandstones and basement rocks along the F- and G-trends define an isochron with a model age of 1753 ± 48 Ma. A secondary isochron is defined predominantly by samples of F-trend sandstone, and has a model age of 4909 ± 85 Ma. This model age represents a primordial Pb source distinct from that which supplied Pb to samples that lie on the 1753 Ma isochron.

High concentrations of leachable U in basement rocks in the discovery zone are associated with high concentrations of As, Co, Ni, Cu, and Zn, which are elements typically associated with complex unconformity-type U deposits. The uranium anomalies are also accompanied by high concentrations of P, which reflects the observed phosphate-hosted uranium mineralization (Table 7).

Elevated concentrations of Zr and Th are associated with all the radiogenic sandstone samples on the F- and G-trends, with values of as much as 2210 ppb Zr and 1050 ppb Th (Table 7). Elevated concentrations of Th and LREE, with variable Zr concentrations, are associated with nearly all radiogenic basement samples. Co + Ni + As ± Cu ± Zn anomalies are associated with two radiogenic samples (Table 7).

Table 6.

40Ar/39Ar Analytical Data for I0 Illite and M1 Muscovite

Step36Ar/40Ar39Ar/40ArCa/K40Ar air (%)39Ar (%)40Ar*/39ArKAge (Ma)± 2σStep36Ar/40Ar39Ar/40ArCa/K40Ar air (%)39Ar (%)40Ar*/39ArKAge (Ma)± 2σ
BL06-65-142.8m (Thelon Fmn. sandstone, near unconformity), plateau age = 1337 ±4 MaBL06-60-243.0m (basement rocks, near unconformity), pseudo-plateau age = 1752 ±19 Ma
10.00010.02030.0096.71.647.6712547510.00000.01450.1599.19.368.38160856
20.00010.018397.68.053.2413561520.00000.01360.0698.918.872.69167433
30.00000.02010.0399.011.349.3012841230.00000.01270.0498.714.377.95175135
40.00000.01920.02100.09.552.0013341040.00010.01260.0597.613.877.64174747
50.00000.01910.0299.510.752.2313381450.00010.01270.0698.511.277.77174943
60.00000.01910.0499.717.952.321340860.00010.01250.0698.09.978.64176147
70.00000.01910.0099.826.852.201337670.00000.01270.1299.38.978.06175355
80.00000.01930.01100.012.751.921332980.00000.01250.3599.43.779.361772134
90.00000.02890.01100.00.634.5898718290.00020.01770.4495.210.253.83136649
100.00030.01940.2490.60.946.791237133
BL98-52-78.1m (Thelon Fmn. sandstone, discovery zone), pseudo-plateau age = 1302 ±11 MaBL06-60-243.0m (duplicate), plateau age = 1738 ±14 Ma
10.00000.02340.9399.93.842.7411578210.00080.012676.80.360.7914861257
20.00000.02200.8698.622.144.9012001420.00000.015099.711.466.30157639
30.00000.02070.78100.014.448.3212652430.00000.01310.0499.623.976.17172619
40.00000.01990.80100.022.650.1613001540.00000.01300.0199.516.676.46173022
50.00000.01960.8399.417.750.6013081950.00000.01270.0399.912.078.39175833
60.00000.01971.07100.08.950.7013104060.00000.01290.0399.58.777.16174050
70.00000.02162.0899.84.446.31122710770.00000.01260.0199.27.179.01176759
80.00010.03857.2098.23.925.4977514280.00000.01260.0099.013.978.82176430
90.00000.108150.2699.42.49.2031917590.00010.01340.0297.96.172.86167770
JP-2-219.6m (Thelon Fmn. sandstone), plateau age = 1339 ±6 MaBL06-65-170.0m (basement rocks, fault zone), pseudo-plateau age = 1758 ±7 Ma
10.00000.01990.0098.65.549.4812884310.00000.014098.83.170.76164592
20.00000.01950.0299.710.051.1913192320.00000.01310.0699.023.975.35171415
30.00000.01920.0399.56.951.9313333730.00000.01270.0099.320.278.29175611
40.00000.01910.0399.511.052.0313342240.00000.01260.0499.313.778.82176410
50.00000.01910.0399.512.352.1713372050.00010.01260.0998.49.177.90175115
60.00000.01900.0399.416.352.4513421560.00000.01330.0699.111.374.80170613
70.00000.01900.0099.829.452.511343970.00000.01340.0299.815.174.52170115
80.00030.02480.6891.28.636.8110356180.00000.01440.1398.73.568.80161540
Step36Ar/40Ar39Ar/40ArCa/K40Ar air (%)39Ar (%)40Ar*/39ArKAge (Ma)± 2σStep36Ar/40Ar39Ar/40ArCa/K40Ar air (%)39Ar (%)40Ar*/39ArKAge (Ma)± 2σ
BL06-65-142.8m (Thelon Fmn. sandstone, near unconformity), plateau age = 1337 ±4 MaBL06-60-243.0m (basement rocks, near unconformity), pseudo-plateau age = 1752 ±19 Ma
10.00010.02030.0096.71.647.6712547510.00000.01450.1599.19.368.38160856
20.00010.018397.68.053.2413561520.00000.01360.0698.918.872.69167433
30.00000.02010.0399.011.349.3012841230.00000.01270.0498.714.377.95175135
40.00000.01920.02100.09.552.0013341040.00010.01260.0597.613.877.64174747
50.00000.01910.0299.510.752.2313381450.00010.01270.0698.511.277.77174943
60.00000.01910.0499.717.952.321340860.00010.01250.0698.09.978.64176147
70.00000.01910.0099.826.852.201337670.00000.01270.1299.38.978.06175355
80.00000.01930.01100.012.751.921332980.00000.01250.3599.43.779.361772134
90.00000.02890.01100.00.634.5898718290.00020.01770.4495.210.253.83136649
100.00030.01940.2490.60.946.791237133
BL98-52-78.1m (Thelon Fmn. sandstone, discovery zone), pseudo-plateau age = 1302 ±11 MaBL06-60-243.0m (duplicate), plateau age = 1738 ±14 Ma
10.00000.02340.9399.93.842.7411578210.00080.012676.80.360.7914861257
20.00000.02200.8698.622.144.9012001420.00000.015099.711.466.30157639
30.00000.02070.78100.014.448.3212652430.00000.01310.0499.623.976.17172619
40.00000.01990.80100.022.650.1613001540.00000.01300.0199.516.676.46173022
50.00000.01960.8399.417.750.6013081950.00000.01270.0399.912.078.39175833
60.00000.01971.07100.08.950.7013104060.00000.01290.0399.58.777.16174050
70.00000.02162.0899.84.446.31122710770.00000.01260.0199.27.179.01176759
80.00010.03857.2098.23.925.4977514280.00000.01260.0099.013.978.82176430
90.00000.108150.2699.42.49.2031917590.00010.01340.0297.96.172.86167770
JP-2-219.6m (Thelon Fmn. sandstone), plateau age = 1339 ±6 MaBL06-65-170.0m (basement rocks, fault zone), pseudo-plateau age = 1758 ±7 Ma
10.00000.01990.0098.65.549.4812884310.00000.014098.83.170.76164592
20.00000.01950.0299.710.051.1913192320.00000.01310.0699.023.975.35171415
30.00000.01920.0399.56.951.9313333730.00000.01270.0099.320.278.29175611
40.00000.01910.0399.511.052.0313342240.00000.01260.0499.313.778.82176410
50.00000.01910.0399.512.352.1713372050.00010.01260.0998.49.177.90175115
60.00000.01900.0399.416.352.4513421560.00000.01330.0699.111.374.80170613
70.00000.01900.0099.829.452.511343970.00000.01340.0299.815.174.52170115
80.00030.02480.6891.28.636.8110356180.00000.01440.1398.73.568.80161540

Notes: ✓ = step used in calculation of weighted plateau and pseudoplateau age

Fig. 12.

The 40Ar/39Ar age spectra for three samples of sandstone-hosted Ml muscovite, one sample of basement-hosted Ml muscovite, and one sample of I0 illite from a basement fault zone.

Fig. 12.

The 40Ar/39Ar age spectra for three samples of sandstone-hosted Ml muscovite, one sample of basement-hosted Ml muscovite, and one sample of I0 illite from a basement fault zone.

Fig. 13.

a. Stratigraphic sections of selected drill holes on F-trend accompanied by plots of 207Pb/206Pb ratios. Drill hole BL98-52 intersects the discovery zone. b. Stratigraphic sections of selected drill holes on the G-trend accompanied by plots of 207Pb/206Pb ratios. See Holk et al. (2003) for similar plots from drill holes in the eastern Thelon, Athabasca and Kombolgie basins.

Fig. 13.

a. Stratigraphic sections of selected drill holes on F-trend accompanied by plots of 207Pb/206Pb ratios. Drill hole BL98-52 intersects the discovery zone. b. Stratigraphic sections of selected drill holes on the G-trend accompanied by plots of 207Pb/206Pb ratios. See Holk et al. (2003) for similar plots from drill holes in the eastern Thelon, Athabasca and Kombolgie basins.

Table 7.

U and Pb Isotope Ratios and Selected Elemental Concentrations of Weak Acid Leachates from Boomerang Lake

Sample no.Lith.Location206Pb/204Pb207Pb/204Pb207Pb/206Pb238U/206PbP (ppb)V (ppb)Co (ppb)Ni (ppb)Cu (ppb)Zn (ppb)As (ppb)Zr (ppb)Ce (ppb)Th (ppb)U (ppb)
BL83-22-61.0ssF-trend22.318.00.812.268090<DL<DL680210<DL160<DL<DL70
BL83-22-68.8ssF-trend21.417.10.801.6128070<DL<DL740270<DL380<DL<DL<DL
BL83-22-91.0ssF-trend29.717.40.59317.0647070<DL501760360140290<DL<DL2460
BL83-22-93.3ssF-trend32.016.30.51231.599901030<DL350205016404202009015019000
BL83-22-94.4pgnF-trend24.416.30.672.6460007030426019806804550602001560470770
BL83-22-98.0pgnF-trend28.816.90.580.516000135092023905602960<DL3002040130<DL
BL83-22-104.5pgnF-trend23.816.20.681.3619020907004404801330<DL4701890210500
BL83-22-111.1pgnF-trend21.715.90.731.01090380<DL100570560<DL840830810280
BL83-22-114.0pgnF-trend20.916.00.772.0161024010706407980600<DL168045013201290
BL98-52-66.5ssF-trend18.015.50.8611.12670480<DL507301010<DL11060<DL200
BL98-52-70.3ssF-trend19.917.20.874.42500<DL<DL50740380<DL100<DL<DL70
BL98-52-75.3ssF-trend24.316.70.698.219000080<DL190710320150250430350720
BL98-52-78.1ssF-trend26.417.00.640.52200000270<DL704002300230166011801901520
BL98-52-82.2ssF-trend21.115.90.7527.841702807005801420240200<DL<DL<DL1840
BL98-52-83.6pgnF-trend31.816.90.5310.81800000400060000270003100031000250007802970170023000
BL98-52-87.0pgnF-trend27.816.40.595.7450000394029000037000073803200047000042085609405180
BL98-52-88.8pgnF-trend27.716.50.60155.71000001000057000028000013000210008200004103700056309300
BL98-52-90.7pgnF-trend32.217.70.5512.094504003360222029904270140110840140440
BL98-52-92.6pgnF-trend33.318.10.5430.2803101960133010202160<DL<DL76080640
BL98-56-78.3ssF-trend26.121.80.849.6n.a.n.a.9040700830302502010140
BL98-56-100.7ssF-trend18.615.40.8256.3n.a.n.a.28012011804050406040201310
BL98-56-102.8pgnF-trend30.116.60.554.7110001880<DL9004201500<DL2501930230390
BL98-56-160.0pgnF-trend32.217.40.545.1170000250<DL<DL460810<DL603380<DL240
BL92-41-79.5ssF-trend22.316.20.735.42200070<DL<DL950630<DL150120180220
BL92-41-122.4pgnF-trend30.117.10.571.238000<DL<DL<DL<DL2540<DL<DL2280100170
BL92-41-165.9pgnF-trend27.716.80.600.9460000<DL<DL<DL7201600<DL<DL2320<DL240
BL98-58-136.7pgnF-trend33.017.00.527.496039804810<DL6709930460<DL21409805960
BL98-58-138.2pgnF-trend20.815.80.761.71600057802150<DL1840383060<DL1100250350
BL98-58-143.9pgnF-trend20.415.90.782.021002660<DL<DL3540870<DL<DL298023001050
BL98-58-155.0pgnF-trend22.115.80.711.8120001160<DL<DL<DL870<DL<DL2810310280
BL98-58-178.3pgnF-trend40.418.20.452.9240000<DL<DL<DL<DL1360<DL<DL3020120180
BL91-34-148.2ssF-trend25.320.30.800.6179060<DL<DL920560<DL150240<DL<DL
BL91-34-154.1pgnF-trend28.917.00.5912.5139041208101320700285011014010403902060
BL91-34-169.1pgnF-trend23.516.40.702.957301010430194014801700<DL58018507405050
BL06-61-97.5ssF-trend24.119.50.813.73030100400<DL1210370<DL<DL<DL<DL100
BL06-61-100.3ssF-trend20.016.60.830.6192070410<DL1830650<DL<DL<DL<DL50
BL06-61-108.8ssF-trend28.523.70.837.82510<DL740<DL650260<DL<DL<DL<DL130
BL06-61-117.0ssF-trend25.521.10.831.52120<DL260<DL860240<DL<DL<DL<DL<DL
BL06-61-121.7ssF-trend28.023.80.853.13500<DL140<DL530200<DL<DL<DL<DL<DL
BL06-61-127.6ssF-trend32.225.50.7928.41800090270<DL610370<DL<DL120<DL290
BL06-61-135.0ssF-trend27.223.30.862.63380<DL610<DL770510<DL<DL<DL<DL<DL
BL06-61-144.0ssF-trend22.819.90.871.64850<DL790<DL1340390<DL<DL<DL<DL<DL
BL06-61-147.5ssF-trend33.627.70.831.24220<DL780<DL980610<DL<DL<DL<DL<DL
BL06-61-156.0ssF-trend23.718.50.780.91610<DL270<DL850260<DL<DL<DL<DL<DL
BL06-61-165.0ssF-trend25.118.60.740.41920<DL330<DL520170<DL<DL<DL<DL<DL
BL06-61-169.5ssF-trend24.219.20.791.61820<DL370<DL620460<DL<DL160<DL<DL
BL06-61-176.5ssF-trend24.917.30.702.02230<DL1205054036090<DL410<DL80
BL06-61-186.2ssF-trend68.121.00.313.44300000490190210530310850125024802703190
BL06-61-187.6ssF-trend49.521.10.432.212000013015070570260801101280210230
BL06-61-190.7ssF-trend26.516.60.624.2100000270370<DL790620<DL130260<DL630
BL06-61-199.1pgnF-trend67.021.50.328.5n.a.n.a.25024043047011012031803301220
BL06-61-208.8pgnF-trend27.817.40.639.6n.a.n.a.50067064014701001802500400820
BL06-61-225.7pgnF-trend18.416.90.920.6n.a.n.a.220280460870<DL605110650200
BL06-61-237.6pgnF-trend24.215.80.6511.5n.a.n.a.320130064035907030519012101130
BL91-38-253.8pgnF-trend35.317.60.503.1n.a.n.a.19017057025501802003190350390
BL91-38-260.8pgnF-trend70.421.20.303.0n.a.n.a.ll012087027002403002330240450
BL06-60-104.5ssF-trend2l.l16.00.751.1n.a.n.a.26050350220<DL60704060
BL06-60-233.7ssF-trend24.218.00.7438.6n.a.n.a.430902802260<DL4014040310
BL06-60-235.2pgnF-trend51.7l9.l0.374.6n.a.n.a.6105702803220ll03904590740530
BL06-60-244.0pgnF-trend38.117.30.467.7n.a.n.a.1808208909901002005670950360
BL92-45-107.2ssF-trend20.216.40.811.1n.a.n.a.<DL<DL920460<DL<DL10<DL30
BL92-45-119.3ssF-trend19.516.50.852.2n.a.n.a.<DL<DL690740<DL<DL10<DL50
BL92-45-129.5ssF-trend20.216.00.794.9n.a.n.a.7030970620<DL<DL<DL<DL130
BL92-45-136.8ssF-trend22.117.30.780.9n.a.n.a.<DL<DL91085030<DL2010<DL
BL92-45-138.0pgnF-trend25.116.80.6718.2n.a.n.a.<DL100510122040<DL230130690
BL92-45-142.0pgnF-trend40.7l9.l0.4734.5n.a.n.a.<DL140780310050<DL16401601800
BL92-45-152.2pgnF-trend269.342.30.168.0n.a.n.a.271028201510307025041023704606020
BL92-43-86.9ssF-trend20.4l6.l0.791.2n.a.n.a.10030830960<DL140202030
BL92-43-96.3ssF-trend29.222.10.760.7n.a.n.a.10030179064040<DL201030
BL92-43-110.9ssF-trend18.615.00.810.7n.a.n.a.ll03012l01070807010080
BL92-43-122.4ssF-trend20.716.40.793.8n.a.n.a.14060800700404013040ll0
BL92-43-123.8ssF-trend19.815.50.780.7n.a.n.a.ll0<DL10801080<DL160<DL<DL<DL
BL92-43-133.0ssF-trend282.640.70.144.3n.a.n.a.12017010108701170153017402307920
BL92-43-147.0pgnF-trend26.816.20.619.2n.a.n.a.2305107901760ll0<DL2100190620
BL92-43-173.8pgnF-trend45.418.30.403.4n.a.n.a.25072063059601402605830270460
BL92-43-189.8pgnF-trend34.7l7.l0.492.3n.a.n.a.8502600108051001701702480100380
BL92-43-205.9pgnF-trend43.019.20.453.2n.a.n.a.360790109028001701903140130330
BL06-65-69.4ssF-trend29.823.40.791.6n.a.n.a.310405005804020302020
BL06-65-87.4ssF-trend*0.665.3n.a.n.a.12208086061040<DL101060
BL06-65-99.4ssF-trend19.315.50.812.3n.a.n.a.2504097056030<DL20<DL70
BL06-65-111.7ssF-trendl9.ll5.l0.7912.7n.a.n.a.150<DL5702630<DL30<DL<DL120
BL06-65-123.7ssF-trend23.318.70.8010.4n.a.n.a.1903058054030101010170
BL06-65-132.5ssF-trend69.820.40.293.9n.a.n.a.330704201800600144031205702960
BL06-65-142.9ssF-trend**0.6912.4n.a.n.a.4205024030060<DLll04040
BL06-65-144.3pgnF-trend28.615.70.550.8n.a.n.a.1508073079090<DL138012040
BL06-65-147.3pgnF-trend32.616.80.524.2n.a.n.a.17070260310210<DL195078090
BL06-65-162.8pgnF-trend39.617.50.4426.0n.a.n.a.9750430182077012060400050700
BL06-65-170.0pgnF-trend63.120.90.3334.2n.a.n.a.130ll06304502508014000330920
BL06-65-177.3pgnF-trend30.316.60.550.8n.a.n.a.12l08201970650330<DL96020100
BL06-65-198.6pgnF-trend31.617.30.550.4n.a.n.a.650390500900ll030770<DL<DL
BL06-65-222.4pgnF-trend36.216.80.460.6n.a.n.a.61304120185024408403906090760570
BL92-47-124.0ssF-trend25.520.00.7824.3n.a.n.a.190801990175060<DL3040370
BL92-48-110.2ssF-trend24.517.90.732.0n.a.n.a.904012l0540<DL<DL1205050
BL92-48-202.1ssF-trend22.217.20.780.8n.a.n.a.100408702530605402507060
BL92-50-244.1ssF-trend21.4l6.l0.7517.0n.a.n.a.9010062098040<DL330120680
BL92-50-250.0pgnF-trend31.017.00.554.3n.a.n.a.491069902900011904602204400024905160
BL92-50-270.8pgnF-trend31.717.50.556.0n.a.n.a.389063001000022801160170850012401420
BL92-50-280.1pgnF-trend30.616.80.551.4n.a.n.a.2080243013702260230<DL50406501130
BL07-67-43.7ssG-trendll3.225.40.226.4n.a.n.a.ll021062010305102210610010503260
BL07-67-57.6ssG-trend24.816.20.652.5n.a.n.a.3906507903030400140720320270
BL07-67-60.0ggnG-trend26.316.40.622.6n.a.n.a.50709509908080510650410
BL07-67-187.3ggnG-trend52.4l8.l0.3410.3n.a.n.a.300501060690250ll01500018504170
BL07-67-230.2qmsG-trend22.315.90.719.9n.a.n.a.2040690630130501850360530
BL06-64-52.4ssG-trend61.920.00.32366.3n.a.n.a.1330235082015000100056012l066024000
BL06-64-80.2ssG-trend29.220.90.7213.0n.a.n.a.21017010706250<DL<DL15050250
BL06-64-93.5ssG-trend32.820.60.633.0n.a.n.a.50ll0790330<DL305050100
BL06-64-98.0ssG-trend25.816.70.65ll.3n.a.n.a.4605206101140905038050420
BL06-64-111.3ggnG-trend21.415.90.742.0n.a.n.a.40<DL710490ll0402320590100
BL06-62-88.4ssG-trend22.516.20.725.0n.a.n.a.5040750390<DL10013060200
BL06-62-116.6ssG-trend20.815.90.7612.9n.a.n.a.3101808602960<DL280ll080640
BL06-62-155.8ssG-trend31.516.90.546.1n.a.n.a.8014069050011010027050310
BL06-62-220.9qmsG-trend25.116.30.653.4n.a.n.a.13018077054026030950770210
BL06-62-252.2qmsG-trend25.416.40.655.5n.a.n.a.4080580190120401680490250
BL06-63-250.3ssG-trend25.716.50.641.1n.a.n.a.20<DL810470<DL30301090
BL06-63-300.2ssG-trend22.116.10.730.3n.a.n.a.105093034012090702020
BL06-63-315.5ssG-trend23.016.20.711.1n.a.n.a.210150600530220401703050
BL06-63-318.1qmsG-trend21.916.20.746.5n.a.n.a.9020094031038020320220240
BL07-69-55.0ssG-trend18.915.40.828.6n.a.n.a.20<DL840310<DL70180100180
BL07-69-84.8ssG-trend17.815.10.853.1n.a.n.a.10<DL830190<DL30302050
BL07-69-126.1ssG-trend20.215.60.777.5n.a.n.a.10101020360<DL404040200
BL07-69-165.1ssG-trend18.815.50.826.3n.a.n.a.0<DL6802301040302090
BL07-69-205.0ssG-trend25.016.60.667.6n.a.n.a.1040135026060703030200
BL07-69-230.2ssG-trend35.317.30.495.5n.a.n.a.601007203901901301150200220
BL07-69-239.7ssG-trend19.515.50.790.3n.a.n.a.2040101042090100870390520
BL07-69-250.2ssG-trend55.119.50.354.8n.a.n.a.10309805801102071025060
BL07-69-256.2ssG-trend19.315.40.800.7n.a.n.a.80<DL6309003401305670270250
BL07-69-261.9ssG-trend35.418.20.529.2n.a.n.a.40<DL8104102101201230210220
BL07-69-266.0ggnG-trend26.416.30.625.9n.a.n.a.20401070440130110910420550
BL07-69-272.9ggnG-trend20.015.60.781.4n.a.n.a.10309505301003065024050
BL07-69-285.9ggnG-trend19.715.60.792.0n.a.n.a.6060730120038080885037080
BL07-69-311.5ggnG-trend37.517.80.483.2n.a.n.a.80606808903001305720280260
BL07-69-337.4ggnG-trend31.517.20.551.8n.a.n.a.1101106307608090315026090
BL07-69-343.1qmsG-trend128.627.40.215.8n.a.n.a.60130102057062031017704901500
BL07-69-356.3qmsG-trend31.116.80.543.5n.a.n.a.5060530210180301880700220
BL07-69-377.9qmsG-trend36.617.30.4718.9n.a.n.a.4090560450140301020510860
BL07-69-393.3qmsG-trend20.416.00.780.8n.a.n.a.305045026080301120280230
BL07-68-118.2ssG-trend21.616.00.741.2n.a.n.a.2030102016405028014060110
BL07-68-238.1ssG-trend21.215.90.754.8n.a.n.a.3070840500<DL150170120240
BL07-68-417.5ssG-trend173.631.80.184.5n.a.n.a.1040380290330137010103301610
BL07-68-431.4qmsG-trend24.316.40.670.7n.a.n.a.2020580140609044011030
BL07-70-40.4ssG-trend20.616.10.783.6n.a.n.a.80<DL910390<DL1307030220
BL07-70-71.1ssG-trend22.116.30.741.2n.a.n.a.70<DL80049040280470220240
BL07-70-101.1ssG-trend25.016.80.671.7n.a.n.a.702098035040130190140460
BL07-70-130.3ssG-trend30.018.40.616.2n.a.n.a.11014069052070<DL200170650
BL07-70-160.2ssG-trend49.719.30.393.7n.a.n.a.330280490800170146016009801450
BL07-70-190.1ssG-trend24.917.60.711.6n.a.n.a.6030550320<DL<DL404050
BL07-70-210.8ssG-trend70.921.10.303.8n.a.n.a.7409201810103017102840467015006460
BL07-70-215.1ssG-trend23.816.40.690.4n.a.n.a.201708302501603072020020
BL07-70-220.6ssG-trend22.117.50.791.8n.a.n.a.70<DL390320100<DL1806090
BL07-70-250.9ssG-trend21.216.60.781.7n.a.n.a.602094024010050<DL8080
BL07-70-280.0ssG-trend24.017.80.740.3n.a.n.a.6040620460<DL40807020
BL07-70-310.1ssG-trend109.126.30.244.0n.a.n.a.140430260320310136029507102060
BL07-70-339.9ssG-trend20.316.50.810.8n.a.n.a.903085069030<DL24014070
BL07-70-360.4ssG-trend26.717.10.643.3n.a.n.a.703010002406040110120190
BL07-70-370.4ssG-trend260.241.80.164.1n.a.n.a.24029083026088099021003404870
BL07-70-378.9ssG-trend29.218.20.622.3n.a.n.a.250606302406011060110120
BL07-70-386.5qmsG-trend43.018.30.431.4n.a.n.a.170170400370990602905001010
BL07-70-391.3qmsG-trend34.418.50.548.3n.a.n.a.9012066015903105018801020700
BL07-70-410.0qmsG-trend59.019.40.3313.3n.a.n.a.130120720340350150410016602360
BL07-70-433.3qmsG-trend21.616.20.751.5n.a.n.a.6302101150840330210250001890770
BL07-70-447.7qmsG-trend57.720.40.355.3n.a.n.a.1802206706304402001100015501110
Sample no.Lith.Location206Pb/204Pb207Pb/204Pb207Pb/206Pb238U/206PbP (ppb)V (ppb)Co (ppb)Ni (ppb)Cu (ppb)Zn (ppb)As (ppb)Zr (ppb)Ce (ppb)Th (ppb)U (ppb)
BL83-22-61.0ssF-trend22.318.00.812.268090<DL<DL680210<DL160<DL<DL70
BL83-22-68.8ssF-trend21.417.10.801.6128070<DL<DL740270<DL380<DL<DL<DL
BL83-22-91.0ssF-trend29.717.40.59317.0647070<DL501760360140290<DL<DL2460
BL83-22-93.3ssF-trend32.016.30.51231.599901030<DL350205016404202009015019000
BL83-22-94.4pgnF-trend24.416.30.672.6460007030426019806804550602001560470770
BL83-22-98.0pgnF-trend28.816.90.580.516000135092023905602960<DL3002040130<DL
BL83-22-104.5pgnF-trend23.816.20.681.3619020907004404801330<DL4701890210500
BL83-22-111.1pgnF-trend21.715.90.731.01090380<DL100570560<DL840830810280
BL83-22-114.0pgnF-trend20.916.00.772.0161024010706407980600<DL168045013201290
BL98-52-66.5ssF-trend18.015.50.8611.12670480<DL507301010<DL11060<DL200
BL98-52-70.3ssF-trend19.917.20.874.42500<DL<DL50740380<DL100<DL<DL70
BL98-52-75.3ssF-trend24.316.70.698.219000080<DL190710320150250430350720
BL98-52-78.1ssF-trend26.417.00.640.52200000270<DL704002300230166011801901520
BL98-52-82.2ssF-trend21.115.90.7527.841702807005801420240200<DL<DL<DL1840
BL98-52-83.6pgnF-trend31.816.90.5310.81800000400060000270003100031000250007802970170023000
BL98-52-87.0pgnF-trend27.816.40.595.7450000394029000037000073803200047000042085609405180
BL98-52-88.8pgnF-trend27.716.50.60155.71000001000057000028000013000210008200004103700056309300
BL98-52-90.7pgnF-trend32.217.70.5512.094504003360222029904270140110840140440
BL98-52-92.6pgnF-trend33.318.10.5430.2803101960133010202160<DL<DL76080640
BL98-56-78.3ssF-trend26.121.80.849.6n.a.n.a.9040700830302502010140
BL98-56-100.7ssF-trend18.615.40.8256.3n.a.n.a.28012011804050406040201310
BL98-56-102.8pgnF-trend30.116.60.554.7110001880<DL9004201500<DL2501930230390
BL98-56-160.0pgnF-trend32.217.40.545.1170000250<DL<DL460810<DL603380<DL240
BL92-41-79.5ssF-trend22.316.20.735.42200070<DL<DL950630<DL150120180220
BL92-41-122.4pgnF-trend30.117.10.571.238000<DL<DL<DL<DL2540<DL<DL2280100170
BL92-41-165.9pgnF-trend27.716.80.600.9460000<DL<DL<DL7201600<DL<DL2320<DL240
BL98-58-136.7pgnF-trend33.017.00.527.496039804810<DL6709930460<DL21409805960
BL98-58-138.2pgnF-trend20.815.80.761.71600057802150<DL1840383060<DL1100250350
BL98-58-143.9pgnF-trend20.415.90.782.021002660<DL<DL3540870<DL<DL298023001050
BL98-58-155.0pgnF-trend22.115.80.711.8120001160<DL<DL<DL870<DL<DL2810310280
BL98-58-178.3pgnF-trend40.418.20.452.9240000<DL<DL<DL<DL1360<DL<DL3020120180
BL91-34-148.2ssF-trend25.320.30.800.6179060<DL<DL920560<DL150240<DL<DL
BL91-34-154.1pgnF-trend28.917.00.5912.5139041208101320700285011014010403902060
BL91-34-169.1pgnF-trend23.516.40.702.957301010430194014801700<DL58018507405050
BL06-61-97.5ssF-trend24.119.50.813.73030100400<DL1210370<DL<DL<DL<DL100
BL06-61-100.3ssF-trend20.016.60.830.6192070410<DL1830650<DL<DL<DL<DL50
BL06-61-108.8ssF-trend28.523.70.837.82510<DL740<DL650260<DL<DL<DL<DL130
BL06-61-117.0ssF-trend25.521.10.831.52120<DL260<DL860240<DL<DL<DL<DL<DL
BL06-61-121.7ssF-trend28.023.80.853.13500<DL140<DL530200<DL<DL<DL<DL<DL
BL06-61-127.6ssF-trend32.225.50.7928.41800090270<DL610370<DL<DL120<DL290
BL06-61-135.0ssF-trend27.223.30.862.63380<DL610<DL770510<DL<DL<DL<DL<DL
BL06-61-144.0ssF-trend22.819.90.871.64850<DL790<DL1340390<DL<DL<DL<DL<DL
BL06-61-147.5ssF-trend33.627.70.831.24220<DL780<DL980610<DL<DL<DL<DL<DL
BL06-61-156.0ssF-trend23.718.50.780.91610<DL270<DL850260<DL<DL<DL<DL<DL
BL06-61-165.0ssF-trend25.118.60.740.41920<DL330<DL520170<DL<DL<DL<DL<DL
BL06-61-169.5ssF-trend24.219.20.791.61820<DL370<DL620460<DL<DL160<DL<DL
BL06-61-176.5ssF-trend24.917.30.702.02230<DL1205054036090<DL410<DL80
BL06-61-186.2ssF-trend68.121.00.313.44300000490190210530310850125024802703190
BL06-61-187.6ssF-trend49.521.10.432.212000013015070570260801101280210230
BL06-61-190.7ssF-trend26.516.60.624.2100000270370<DL790620<DL130260<DL630
BL06-61-199.1pgnF-trend67.021.50.328.5n.a.n.a.25024043047011012031803301220
BL06-61-208.8pgnF-trend27.817.40.639.6n.a.n.a.50067064014701001802500400820
BL06-61-225.7pgnF-trend18.416.90.920.6n.a.n.a.220280460870<DL605110650200
BL06-61-237.6pgnF-trend24.215.80.6511.5n.a.n.a.320130064035907030519012101130
BL91-38-253.8pgnF-trend35.317.60.503.1n.a.n.a.19017057025501802003190350390
BL91-38-260.8pgnF-trend70.421.20.303.0n.a.n.a.ll012087027002403002330240450
BL06-60-104.5ssF-trend2l.l16.00.751.1n.a.n.a.26050350220<DL60704060
BL06-60-233.7ssF-trend24.218.00.7438.6n.a.n.a.430902802260<DL4014040310
BL06-60-235.2pgnF-trend51.7l9.l0.374.6n.a.n.a.6105702803220ll03904590740530
BL06-60-244.0pgnF-trend38.117.30.467.7n.a.n.a.1808208909901002005670950360
BL92-45-107.2ssF-trend20.216.40.811.1n.a.n.a.<DL<DL920460<DL<DL10<DL30
BL92-45-119.3ssF-trend19.516.50.852.2n.a.n.a.<DL<DL690740<DL<DL10<DL50
BL92-45-129.5ssF-trend20.216.00.794.9n.a.n.a.7030970620<DL<DL<DL<DL130
BL92-45-136.8ssF-trend22.117.30.780.9n.a.n.a.<DL<DL91085030<DL2010<DL
BL92-45-138.0pgnF-trend25.116.80.6718.2n.a.n.a.<DL100510122040<DL230130690
BL92-45-142.0pgnF-trend40.7l9.l0.4734.5n.a.n.a.<DL140780310050<DL16401601800
BL92-45-152.2pgnF-trend269.342.30.168.0n.a.n.a.271028201510307025041023704606020
BL92-43-86.9ssF-trend20.4l6.l0.791.2n.a.n.a.10030830960<DL140202030
BL92-43-96.3ssF-trend29.222.10.760.7n.a.n.a.10030179064040<DL201030
BL92-43-110.9ssF-trend18.615.00.810.7n.a.n.a.ll03012l01070807010080
BL92-43-122.4ssF-trend20.716.40.793.8n.a.n.a.14060800700404013040ll0
BL92-43-123.8ssF-trend19.815.50.780.7n.a.n.a.ll0<DL10801080<DL160<DL<DL<DL
BL92-43-133.0ssF-trend282.640.70.144.3n.a.n.a.12017010108701170153017402307920
BL92-43-147.0pgnF-trend26.816.20.619.2n.a.n.a.2305107901760ll0<DL2100190620
BL92-43-173.8pgnF-trend45.418.30.403.4n.a.n.a.25072063059601402605830270460
BL92-43-189.8pgnF-trend34.7l7.l0.492.3n.a.n.a.8502600108051001701702480100380
BL92-43-205.9pgnF-trend43.019.20.453.2n.a.n.a.360790109028001701903140130330
BL06-65-69.4ssF-trend29.823.40.791.6n.a.n.a.310405005804020302020
BL06-65-87.4ssF-trend*0.665.3n.a.n.a.12208086061040<DL101060
BL06-65-99.4ssF-trend19.315.50.812.3n.a.n.a.2504097056030<DL20<DL70
BL06-65-111.7ssF-trendl9.ll5.l0.7912.7n.a.n.a.150<DL5702630<DL30<DL<DL120
BL06-65-123.7ssF-trend23.318.70.8010.4n.a.n.a.1903058054030101010170
BL06-65-132.5ssF-trend69.820.40.293.9n.a.n.a.330704201800600144031205702960
BL06-65-142.9ssF-trend**0.6912.4n.a.n.a.4205024030060<DLll04040
BL06-65-144.3pgnF-trend28.615.70.550.8n.a.n.a.1508073079090<DL138012040
BL06-65-147.3pgnF-trend32.616.80.524.2n.a.n.a.17070260310210<DL195078090
BL06-65-162.8pgnF-trend39.617.50.4426.0n.a.n.a.9750430182077012060400050700
BL06-65-170.0pgnF-trend63.120.90.3334.2n.a.n.a.130ll06304502508014000330920
BL06-65-177.3pgnF-trend30.316.60.550.8n.a.n.a.12l08201970650330<DL96020100
BL06-65-198.6pgnF-trend31.617.30.550.4n.a.n.a.650390500900ll030770<DL<DL
BL06-65-222.4pgnF-trend36.216.80.460.6n.a.n.a.61304120185024408403906090760570
BL92-47-124.0ssF-trend25.520.00.7824.3n.a.n.a.190801990175060<DL3040370
BL92-48-110.2ssF-trend24.517.90.732.0n.a.n.a.904012l0540<DL<DL1205050
BL92-48-202.1ssF-trend22.217.20.780.8n.a.n.a.100408702530605402507060
BL92-50-244.1ssF-trend21.4l6.l0.7517.0n.a.n.a.9010062098040<DL330120680
BL92-50-250.0pgnF-trend31.017.00.554.3n.a.n.a.491069902900011904602204400024905160
BL92-50-270.8pgnF-trend31.717.50.556.0n.a.n.a.389063001000022801160170850012401420
BL92-50-280.1pgnF-trend30.616.80.551.4n.a.n.a.2080243013702260230<DL50406501130
BL07-67-43.7ssG-trendll3.225.40.226.4n.a.n.a.ll021062010305102210610010503260
BL07-67-57.6ssG-trend24.816.20.652.5n.a.n.a.3906507903030400140720320270
BL07-67-60.0ggnG-trend26.316.40.622.6n.a.n.a.50709509908080510650410
BL07-67-187.3ggnG-trend52.4l8.l0.3410.3n.a.n.a.300501060690250ll01500018504170
BL07-67-230.2qmsG-trend22.315.90.719.9n.a.n.a.2040690630130501850360530
BL06-64-52.4ssG-trend61.920.00.32366.3n.a.n.a.1330235082015000100056012l066024000
BL06-64-80.2ssG-trend29.220.90.7213.0n.a.n.a.21017010706250<DL<DL15050250
BL06-64-93.5ssG-trend32.820.60.633.0n.a.n.a.50ll0790330<DL305050100
BL06-64-98.0ssG-trend25.816.70.65ll.3n.a.n.a.4605206101140905038050420
BL06-64-111.3ggnG-trend21.415.90.742.0n.a.n.a.40<DL710490ll0402320590100
BL06-62-88.4ssG-trend22.516.20.725.0n.a.n.a.5040750390<DL10013060200
BL06-62-116.6ssG-trend20.815.90.7612.9n.a.n.a.3101808602960<DL280ll080640
BL06-62-155.8ssG-trend31.516.90.546.1n.a.n.a.8014069050011010027050310
BL06-62-220.9qmsG-trend25.116.30.653.4n.a.n.a.13018077054026030950770210
BL06-62-252.2qmsG-trend25.416.40.655.5n.a.n.a.4080580190120401680490250
BL06-63-250.3ssG-trend25.716.50.641.1n.a.n.a.20<DL810470<DL30301090
BL06-63-300.2ssG-trend22.116.10.730.3n.a.n.a.105093034012090702020
BL06-63-315.5ssG-trend23.016.20.711.1n.a.n.a.210150600530220401703050
BL06-63-318.1qmsG-trend21.916.20.746.5n.a.n.a.9020094031038020320220240
BL07-69-55.0ssG-trend18.915.40.828.6n.a.n.a.20<DL840310<DL70180100180
BL07-69-84.8ssG-trend17.815.10.853.1n.a.n.a.10<DL830190<DL30302050
BL07-69-126.1ssG-trend20.215.60.777.5n.a.n.a.10101020360<DL404040200
BL07-69-165.1ssG-trend18.815.50.826.3n.a.n.a.0<DL6802301040302090
BL07-69-205.0ssG-trend25.016.60.667.6n.a.n.a.1040135026060703030200
BL07-69-230.2ssG-trend35.317.30.495.5n.a.n.a.601007203901901301150200220
BL07-69-239.7ssG-trend19.515.50.790.3n.a.n.a.2040101042090100870390520
BL07-69-250.2ssG-trend55.119.50.354.8n.a.n.a.10309805801102071025060
BL07-69-256.2ssG-trend19.315.40.800.7n.a.n.a.80<DL6309003401305670270250
BL07-69-261.9ssG-trend35.418.20.529.2n.a.n.a.40<DL8104102101201230210220
BL07-69-266.0ggnG-trend26.416.30.625.9n.a.n.a.20401070440130110910420550
BL07-69-272.9ggnG-trend20.015.60.781.4n.a.n.a.10309505301003065024050
BL07-69-285.9ggnG-trend19.715.60.792.0n.a.n.a.6060730120038080885037080
BL07-69-311.5ggnG-trend37.517.80.483.2n.a.n.a.80606808903001305720280260
BL07-69-337.4ggnG-trend31.517.20.551.8n.a.n.a.1101106307608090315026090
BL07-69-343.1qmsG-trend128.627.40.215.8n.a.n.a.60130102057062031017704901500
BL07-69-356.3qmsG-trend31.116.80.543.5n.a.n.a.5060530210180301880700220
BL07-69-377.9qmsG-trend36.617.30.4718.9n.a.n.a.4090560450140301020510860
BL07-69-393.3qmsG-trend20.416.00.780.8n.a.n.a.305045026080301120280230
BL07-68-118.2ssG-trend21.616.00.741.2n.a.n.a.2030102016405028014060110
BL07-68-238.1ssG-trend21.215.90.754.8n.a.n.a.3070840500<DL150170120240
BL07-68-417.5ssG-trend173.631.80.184.5n.a.n.a.1040380290330137010103301610
BL07-68-431.4qmsG-trend24.316.40.670.7n.a.n.a.2020580140609044011030
BL07-70-40.4ssG-trend20.616.10.783.6n.a.n.a.80<DL910390<DL1307030220
BL07-70-71.1ssG-trend22.116.30.741.2n.a.n.a.70<DL80049040280470220240
BL07-70-101.1ssG-trend25.016.80.671.7n.a.n.a.702098035040130190140460
BL07-70-130.3ssG-trend30.018.40.616.2n.a.n.a.11014069052070<DL200170650
BL07-70-160.2ssG-trend49.719.30.393.7n.a.n.a.330280490800170146016009801450
BL07-70-190.1ssG-trend24.917.60.711.6n.a.n.a.6030550320<DL<DL404050
BL07-70-210.8ssG-trend70.921.10.303.8n.a.n.a.7409201810103017102840467015006460
BL07-70-215.1ssG-trend23.816.40.690.4n.a.n.a.201708302501603072020020
BL07-70-220.6ssG-trend22.117.50.791.8n.a.n.a.70<DL390320100<DL1806090
BL07-70-250.9ssG-trend21.216.60.781.7n.a.n.a.602094024010050<DL8080
BL07-70-280.0ssG-trend24.017.80.740.3n.a.n.a.6040620460<DL40807020
BL07-70-310.1ssG-trend109.126.30.244.0n.a.n.a.140430260320310136029507102060
BL07-70-339.9ssG-trend20.316.50.810.8n.a.n.a.903085069030<DL24014070
BL07-70-360.4ssG-trend26.717.10.643.3n.a.n.a.703010002406040110120190
BL07-70-370.4ssG-trend260.241.80.164.1n.a.n.a.24029083026088099021003404870
BL07-70-378.9ssG-trend29.218.20.622.3n.a.n.a.250606302406011060110120
BL07-70-386.5qmsG-trend43.018.30.431.4n.a.n.a.170170400370990602905001010
BL07-70-391.3qmsG-trend34.418.50.548.3n.a.n.a.9012066015903105018801020700
BL07-70-410.0qmsG-trend59.019.40.3313.3n.a.n.a.130120720340350150410016602360
BL07-70-433.3qmsG-trend21.616.20.751.5n.a.n.a.6302101150840330210250001890770
BL07-70-447.7qmsG-trend57.720.40.355.3n.a.n.a.1802206706304402001100015501110

Notes: Lith. = lithology (ss = Thelon Fmn. sandstone; pgn = paragneiss; ggn = granitic gneiss; qms = quartz+muscovite schist); n.a. = not analyzed; <DL = below analytical detection limit, which is 1 ppb or less for all elements; * = 204Pb below analytical detection limit

Fig. 14.

Plot of 238U/206Pb versus 206Pb/204Pb for all samples at Boomerang Lake, showing the evolution of isotopic ratios from 250 Ma to 1750 Ma (Holk et al., 2003). Radiogenic Pb in all samples is supported by leachable U (indicative of Pb produced in situ) and plots outside the zone of unsupported Pb (hatched area) that is an indicator of a possible nearby uranium deposit.

Fig. 14.

Plot of 238U/206Pb versus 206Pb/204Pb for all samples at Boomerang Lake, showing the evolution of isotopic ratios from 250 Ma to 1750 Ma (Holk et al., 2003). Radiogenic Pb in all samples is supported by leachable U (indicative of Pb produced in situ) and plots outside the zone of unsupported Pb (hatched area) that is an indicator of a possible nearby uranium deposit.

Discussion

Basement rocks and sandstones of the Thelon Formation have been altered by at least five fluids that are distinguished on the basis of mineral paragenesis and stable isotope geochemistry. These include the following: (1) pre-Thelon basin meteoric water, (2) early diagenetic basinal fluid, (3) peak diagenetic basinal fluid, (4) hydrothermal fluid, and (5) recent meteoric water.

Fig. 15.

Plot of 206Pb/204Pb versus 207Pb/204Pb for all samples at Boomerang Lake relative to the common Pb growth curve of Stacey and Kramers (1975). Most sandstone and basement samples from the F-and G-trends lie along a Pb-mixing isochron with an age of 1753 ±48 Ma. F- and G-trend sandstones that have experienced a lesser degree of diagenetic alteration lie along a Pb-mixing isochron with an age of 4909 ± 85 Ma.

Fig. 15.

Plot of 206Pb/204Pb versus 207Pb/204Pb for all samples at Boomerang Lake relative to the common Pb growth curve of Stacey and Kramers (1975). Most sandstone and basement samples from the F-and G-trends lie along a Pb-mixing isochron with an age of 1753 ±48 Ma. F- and G-trend sandstones that have experienced a lesser degree of diagenetic alteration lie along a Pb-mixing isochron with an age of 4909 ± 85 Ma.

Pre-Thelon basin meteoric waters

The assemblage K0 kaolinite + F0 hematite ± I0 illite ± D0 dolomite was formed by subaerial weathering of basement rocks and represents the Thelon paleosol of Gall (1994). The fluids assumed to be in equilibrium with K0 kaolinite and I0 illite at 50°C had δ18Ofluid and δ18Hfluid values that plot near the meteoric water line (Fig. 11a), and are consistent with meteoric waters from low latitudes. The D0 dolomite has similarly low δ18Ofluid values (Table 5; Fig. 11b) that are characteristic of meteoric waters. Paleosol formation occurred at 1758 ±7 Ma based on the 40Ar/39Ar age of I0 illite, which coincides with 1760 to 1753 Ma minimum age of pre-Thelon basin magmatism in the eastern Thelon basin region (LeCheminant et al., 1987; Miller, 1995).

The preservation of this age in I0 illite requires that the mineral did not interact with subsequent fluids, as fluid events in other Proterozoic basins are known to affect the Ar isotopic system of white mica (Polito et al., 2005; Alexandre et al., 2009). Additionally, Sherlock et al. (2003) report closure temperatures ranging from 175° to 275°C for clay-size (<2 µm) muscovite. Based on EMPA data, I0 illite was subjected to temperatures of 200°C during the formation of the Thelon basin, but this did not result in the resetting of the Ar isotope system or significant changes in the Kübler Index, most likely because alteration took place at low fluid/rock ratios. The preservation of low Hinckley indices in two K0 kaolinite samples could have also occurred under similar conditions, whereas the remaining K0 kaolinite samples interacted with later, higher temperature fluids, resulting in recrystallization and increased Hinckley indices.

Early diagenetic basinal fluids

Early diagenesis in sandstones of the Thelon Formation produced the assemblage Q1 quartz + P1 phosphates + Q2 quartz + S1 pyrite (Fig. 5). The P1b fluorapatite and D1 dolomite are present in basement fractures and fault zones, and likely formed from early diagenetic basinal fluids that penetrated the unconformity. Early diagenetic fluids variably interacted with graphitic basement rocks at low water/rock ratios, based on the relationship between increasing δ18Ofluid values and decreasing δ13Cmin values of D1 dolomite. This relationship indicates progressive fluid interaction with both host rock silicates and a 12C-rich source such as graphite, which has δ13Cmin values of –25 ± 5 per mil in basement rocks of the Athabasca basin (Kyser et al., 1989).

Early diagenetic fluids were relatively reducing as the formation of phosphates is favored by conditions of low Eh, in addition to neutral to alkaline pH, high phosphorus activity, and low sulfide activity (Nriagu, 1972; Postma, 1981; Fonseca, 2000). The S1 pyrite formed later under conditions of low Eh and high sulfide activity (Nriagu, 1972). The lack of substituting elements (U, LREE, Y, Sr, and Mn) in P1b fluorapatite suggests low activities of these elements in early diagenetic fluids. It is possible that early diagenetic fluids at Boomerang Lake were not at a suitable temperature or redox state to mobilize uranium.

Peak diagenetic basinal fluids

Peak diagenesis occurred at temperatures of 200° to 250°C and produced the assemblage K1 kaolinite + M1 muscovite + K2 dickite in sandstones of the Thelon Formation and M1 muscovite in basement rocks. The δ18O and δ2H values of fluids in equilibrium with these phyllosilicates contained in sandstone interstices range from 6.7 to 9.4 and –76 to –24 per mil (Table 5; Fig. 11a), respectively, which is consistent with oxidizing, saline, and acidic basinal brines in other Proterozoic to Phanerozoic basins (Wilson and Kyser, 1987; Ayalon and Longstaffe, 1988; Bray et al., 1988; Kotzer and Kyser, 1995; Fayek and Kyser, 1997; Polito et al., 2004, 2005, 2006; Kyser and Cuney, 2008a).

Peak diagenetic fluids reached high enough temperatures to have passed through the so-called thermal leaching window and were probably capable of mobilizing uranium and other metals (Southgate et al., 2006). The δ2Hfluid values associated with K1 kaolinite and K2 dickite are lower than those of seawater, and suggest a meteoric water component to the peak diagenetic fluids. The observed δ18Ofluid variations in K2 dickite suggest that fracture-related and vuggy porosity in sandstones conducted fluids that were slightly less buffered by basinal silicates than the basinal fluids that were locked in sandstone interstices (Fig. 11a). The δ18O and δ2H values of fluids in equilibrium with basement-hosted K0 kaolinite with higher Hinckley indices are similar to those of fluids that produced K1 kaolinite and K2 dickite in sandstones. This suggests that peak diagenetic basinal fluids interacted with basement rocks at these sample locations (Fig. 11a).

Hydrothermal fluids

Hydrothermal siderite and C2 sudoite formed at 200°C from fluids with the highest δ18O and δ2H values at Boomerang Lake (Fig. 11a). In Phanerozoic sedimentary basins, fluids with high δ18O and δ2H values are the most chemically evolved relative to initial meteoric fluids (Clayton et al., 1966; Longstaffe, 2000). Based on the negative δ13Cmin value of –14.5 per mil for siderite, it is suggested that peak diagenetic basinal fluids in the Thelon basin penetrated the unconformity and became isotopically evolved and likely reducing through interaction with sulfide-bearing graphitic basement rocks (Table 5; Fig. 11b). Metals would have been acquired, as represented by the S2 assemblage, as would Mg that formed C2 sudoite. During hydrothermal alteration, a basement fault zone was reactivated (Davidson et al., 1998) and resulted in the injection of evolved peak diagenetic basinal fluids into basal sandstones surrounding the discovery zone, which resulted in the observed distribution of S2 phases and C2 sudoite at this location. Evolved peak diagenetic basinal fluids were also likely responsible for the alteration of M1 muscovite associated with P2 tristramite based on elevated metal contents (Fe, Mg, Cr, and V; see Table 2) in the altered M1 muscovite. This event likely initiated the precipitation of U- and other metal-bearing phases because it provided the opportunity for relatively reducing evolved peak diagenetic basinal fluids to mix with oxidizing peak diagenetic basinal fluids that were capable of transporting U.

Recent meteoric waters

Three samples of K2 dickite from sandstone outcrops have similar δ18Ofluid values, but lower δ2Hfluid values than K2 dickite sampled from drill core (Fig. 11a). Retrograde exchange of H isotopes with recent, low temperature, high latitude meteoric water having low δ2H values (Kyser and Kerrich, 1991; Kotzer and Kyser, 1995) has likely occurred based on the observation that only outcrop samples have been affected by preferential H-isotope exchange.

Hydrostratigraphy of the Thelon Formation and links to hydrothermal alteration

Identification of fluid pathways, or diagenetic aquifers, versus fluid barriers, or diagenetic aquitards (Hiatt et al., 2003; Kyser, 2007), in sandstones of the Thelon Formation at Boomerang Lake is aided by the stratigraphically influenced distribution of peak diagenetic phyllosilicates. The assemblage K1 kaolinite + M1 muscovite + K2 dickite marks strata that conducted peak diagenetic basinal fluids throughout deep burial and were likely diagenetic aquifers. Based on 40Ar/39Ar ages of M1 muscovite in K2 dickite-bearing sandstones (Figs. 6, 12), diagenetic aquifers at Boomerang Lake remained open to fluids throughout peak diagenesis and after, probably until 1302 Ma. The K2 dickite-bearing strata with diagenetic aquifer characteristics are widely distributed in Sequence 3 sandstones that dominate at the G-trend, but occur only sporadically in Sequence 2 sandstones that are prevalent along the F-trend, including a limited distribution in the discovery zone. Moreover, K2 dickite is absent from Sequence 1, the basal unit on the G-trend (Fig. 6).

The assemblage K1 kaolinite + M1 muscovite marks strata that initially conducted peak diagenetic basinal fluids, but then formed diagenetic aquitards and became isolated from later basinal fluids that produced K2 dickite. These strata make up Sequence 1 and are widely distributed in Sequence 2 (Fig. 6). Sequence 1 and 2 sandstones were also segregated from Pb with a model age of 1753 ± 48 Ma, which is present in the remainder of sandstone samples, as they host a high proportion of samples with highly leachable 207Pb (Fig. 6). Certain basement zones underlying Sequence 2 strata on the F-trend, including fault zones that are typically permeable to basinal fluids, were also isolated from peak diagenetic basinal fluids based on the preservation of low temperature, poorly crystalline K0 kaolinite and I0 illite in the Thelon paleosol, and pre-Thelon basin 40Ar/39Ar ages of white mica.

Fluid conditions in Sequence 2 sandstones during hydrothermal alteration are inferred from δ18O values of fluids in equilibrium with M1 muscovite and C2 sudoite, which bracket the hydrothermal alteration event. These minerals have δ18Ofluid values that are generally 3 to 5 per mil higher than δ18Ofluid values of paragenetically similar muscovite, illite, and sudoite in alteration halos associated with Athabasca U deposits (Fig. 11a). This may reflect increased fluid buffering by 18O-rich silicates at a fluid/rock ratio that was low relative to the Athabasca basin, where less buffering by host-rock silicates is indicated (Fig. 11a). Based on these data, Sequence 2 sandstones across the F-trend were not conducting enough potentially U-bearing peak diagenetic basinal fluid to the unconformity during basement fault reactivation and hydrothermal alteration to form an unconformity-type U deposit.

Isolated K2 dickite-bearing strata near the discovery zone indicate limited presence of peak diagenetic basinal fluids, and the little uranium that was provided formed diminutive U-phosphate occurrences following the reaction  

formula

In this reaction, peak diagenetic basinal fluids provided Ca and P ions from the dissolution of P1 phosphates and U+6 through alteration of U-bearing detrital phases (e.g., Wilson and Kyser, 1987; Kotzer and Kyser, 1995; Fayek and Kyser, 1997), transported as a phosphate complex (Kyser and Cuney, 2008b). The Fe2+ or S in S1 pyrite probably acted as reductants for the U. Evolved peak diagenetic basinal fluids at Boomerang Lake were not effectively reduced, possibly due to insufficient interaction with basement rocks because of the fluid-poor conditions recorded in Sequence 2 sandstones. This has discouraging implications for the discovery zone regarding the formation of complex-type unconformity-type uranium deposits, which require basinal fluids both as a source of U and as a reductant upon interaction with reducing basement rock types (Fayek and Kyser, 1997; Kyser and Cuney, 2008a).

Evaluation of radiogenic zones and exploration guidelines

Radiogenic to highly radiogenic Pb, which is present in sandstone and basement-hosted zones on the F- and G-trends, is in nearly all cases associated with elevated Zr and Th, and high 238U/206Pb ratios indicative of radiogenic Pb produced in situ or from a young U source. Many of the radiogenic to highly radiogenic zones on the two trends are coincident with high (Zr+Th)/U in the leachable component (Fig. 16). The ratio (Zr+Th)/U would be expected to decrease approaching an unconformity-related U deposit. Because it does not, the radiogenic Pb in these zones is likely contributed from the decay of U contained in accessory and detrital zircon and monazite. These phases were affected by a combination of physical and chemical processes during pre-Thelon basin faulting and subaerial weathering of basement rocks, as suggested by the 1753 ± 48 Ma 207Pb/206Pb isochron model age of leachable Pb.

These minerals were subsequently incorporated into overlying sandstones of the Thelon Formation as detrital phases, and released the same age Pb to strata during compaction and diagenesis. These zones are not considered to be prospective because they do not display the characteristics of an ideal vector to uranium mineralization, which typically shows anomalously radiogenic Pb, increased concentrations of pathfinder elements, and low 238U/206Pb ratios indicative of excess radiogenic Pb.

There are two zones of highly radiogenic Pb that display lower (Zr+Th)/U ratios, suggesting a decreased contribution of in situ radiogenic Pb by zircon and monazite. One zone, located in the G-trend sandstone (BL06-64-52.4m; Table 7), contains elevated Co + Ni + As + Zn, but is accompanied by high 238U/206Pb ratios (Fig. 14) that are indicative of supported Pb. These characteristics are similar to those displayed in the discovery zone and may represent a similar style of U-phosphate mineralization. The second zone occurs in the F-trend basement rocks (BL92-43-l33.0m and BL92-45-152.2m; Table 7). The 238U/206Pb ratios of the two samples approach the field of unsupported Pb (Fig. 14). The zone also shows elevated Co + Ni + Zn and traces of the hydrothermal assemblage siderite + S2, and is prospective from a geochemical standpoint. The prospectivity of this zone is greatly diminished, however, when the fluid history of overlying Sequence 2 sandstones is taken into consideration, because it is evident that these strata were not conducting U-bearing peak diagenetic basinal fluids during hydrothermal alteration.

Fig. 16.

Plot of 207Pb/206Pb ratios versus (Zr+Th)/U ratios for F- and G-trend samples. High (Zr+Th)/U ratios accompany all highly radiogenic samples, indicating a significant contribution of radiogenic Pb from accessory and detrital zircon and monazite. Decreasing (Zr+Th)/U ratios accompanied by decreasing 207Pb/206Pb ratios represent a prospective trend.

Fig. 16.

Plot of 207Pb/206Pb ratios versus (Zr+Th)/U ratios for F- and G-trend samples. High (Zr+Th)/U ratios accompany all highly radiogenic samples, indicating a significant contribution of radiogenic Pb from accessory and detrital zircon and monazite. Decreasing (Zr+Th)/U ratios accompanied by decreasing 207Pb/206Pb ratios represent a prospective trend.

Intersections of Sequence 3 strata with structurally reactivated basement rocks represent a much more desirable exploration target, as these strata were the diagenetic aquifers that conducted U-bearing peak diagenetic basinal fluids throughout peak diagenesis. Although the G-trend basement lithologies are unproven regarding their potential to host unconformity-related U deposits, the substantial thickness of Sequence 3 diagenetic aquifers certainly warrant further exploration along this trend.

Conclusions

Sandstones and basement rocks intersected during drilling at Boomerang Lake were altered by multiple fluid events, including those associated with paleosol development on basement rocks, basin formation and prolonged diagenesis, and limited hydrothermal alteration. The basement paleosol preserves poorly crystalline, low temperature kaolinite and illite that formed from low-δl8O meteoric waters. Early diagenetic basinal fluids were relatively reducing and produced a phosphate-dominated alteration mineral assemblage. Peak diagenetic basinal fluids had an initial meteoric water component, but became oxidizing basinal brines with high δl8Ofluid values and variable δl8Hfluid values that were capable of transporting uranium. These fluids penetrated the unconformity in the discovery zone and interacted with graphitic basement rocks to become high-δl8O, high-δ2H, chemically evolved peak diagenetic fluids.

The peak diagenetic assemblage K1 kaolinite + M1 muscovite, prevalent in Sequence 2 sandstones that overlie the unconformity on the F-trend, mark strata that were isolated from later peak diagenetic fluids that were widespread in Sequence 3 sandstones and associated with the assemblage K1 kaolinite + M1 muscovite + K2 dickite. This is reflected by the stable isotopic composition of fluids associated with peak diagenetic and hydrothermal alteration minerals at Boomerang Lake, which had comparatively higher δ18O values than paragenetically equivalent Athabasca fluids that migrated under a low fluid/rock regime. Peak diagenetic basinal fluids were not sufficient enough in volume to mobilize significant uranium during hydrothermal alteration and resulted in formation of limited uranium phosphate occurrences in the discovery zone, and were not present in basement zones that preserve low-temperature minerals and pre-Thelon basin 40Ar/39Ar ages.

The discovery zone at Boomerang Lake is marked by modestly radiogenic Pb and very high 238U/206Pb ratios, which is atypical of Athabasca and Kombolgie unconformity-type uranium deposits. Radiogenic to highly radiogenic mobile Pb outside the discovery zone is nearly all supported by leachable U and was likely produced in situ from altered, accessory and detrital zircon and monazite, and not a nearby uranium deposit. The ca. 1750 Ma common Pb model age of radiogenic Pb indicates that the U-Pb isotope system in these minerals was reset during basement weathering and paleosol development. The few samples with lower (Zr+Th)/U ratios represent more prospective areas.

We recommend that future exploration at Boomerang Lake focuses on intersections of dickite-bearing strata and structurally reactivated basement rocks, and that trends of decreasing 207Pb/206Pb and 238U/206Pb ratios, and decreasing (Zr+Th)/U ratios and concentrations of U and pathfinder elements represent an ideal vector to mineralization.

Acknowledgments

The authors thank Don Chipley, Kerry Klassen, Allison Laidlow, Bill McFarlane, April Vuletich, Al Grant, Brad Singer, and Brian Jicha for their analytical efforts. Larry Lahusen and Chris Pettman of Uravan Minerals Inc. provided field logistical support and aided in drafting figures. Paul Alexandre and Jonathan Cloutier are thanked for help with data interpretation and manuscript review. Peter Jones assisted with SEM and electron microprobe analyses at Carleton University, Ottawa, and his expertise was greatly appreciated. Constructive reviews by Rob Kerrich and Michel Cuney were much appreciated, and Thomas Monecke and Richard Goldfarb are thanked for editorial handling. The research was funded by Uravan Minerals Inc., Cameco Corporation, a Society of Economic Geologists Canada Foundation grant, and a Natural Sciences and Engineering Research Council Collaborative Research Development grant.

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Figures & Tables

Fig. 1.

Generalized geological map of the Western Churchill province, Canada, showing the location of the Boomerang Lake unconformity-type uranium prospect in the western Thelon basin. Modified from Davidson and Gandhi (1989). AB = Alberta, MB = Manitoba, NT = Northwest Territories, NU = Nunavut, SK = Saskatchewan.

Fig. 1.

Generalized geological map of the Western Churchill province, Canada, showing the location of the Boomerang Lake unconformity-type uranium prospect in the western Thelon basin. Modified from Davidson and Gandhi (1989). AB = Alberta, MB = Manitoba, NT = Northwest Territories, NU = Nunavut, SK = Saskatchewan.

Fig. 2.

Generalized geological map of the Boomerang Lake uranium prospect. The F- and G-trends are the primary exploration corridors and are defined by the axes of electromagnetic (EM) conductors. Labeled drill holes were used in this study. Stratigraphic sections were measured at drill hole locations shown as a black dot. The Boomerang Lake discovery zone is located near the southwestern end of F-trend. Int. = intermediate.

Fig. 2.

Generalized geological map of the Boomerang Lake uranium prospect. The F- and G-trends are the primary exploration corridors and are defined by the axes of electromagnetic (EM) conductors. Labeled drill holes were used in this study. Stratigraphic sections were measured at drill hole locations shown as a black dot. The Boomerang Lake discovery zone is located near the southwestern end of F-trend. Int. = intermediate.

Fig. 3.

Simplified sections of F- and G-trend exploration corridors at Boomerang Lake. a. Longitudinal section of F-trend. b. Longitudinal section of G-trend. Scale is the same as in Figure 3a. c. Cross section of G-trend. Drill hole locations are shown in Figure 2.

Fig. 3.

Simplified sections of F- and G-trend exploration corridors at Boomerang Lake. a. Longitudinal section of F-trend. b. Longitudinal section of G-trend. Scale is the same as in Figure 3a. c. Cross section of G-trend. Drill hole locations are shown in Figure 2.

Fig. 4.

Cross section of the Boomerang Lake discovery zone. Data compiled from unpublished Urangesellschaft Canada Ltd. and Uravan Minerals Inc. drill logs and Davidson et al. (1998). Drill hole labels in italics were used in this study.

Fig. 4.

Cross section of the Boomerang Lake discovery zone. Data compiled from unpublished Urangesellschaft Canada Ltd. and Uravan Minerals Inc. drill logs and Davidson et al. (1998). Drill hole labels in italics were used in this study.

Fig. 5.

Paragenesis of minerals associated with retrograde metamorphism and weathering of basement rocks, diagenesis, and hydrothermal alteration. The 1757 Ma age of basement weathering is interpreted from Ar-Ar geochronology (see text for discussion), and the 1667 Ma age of early diagenesis is inferred from Davis et al. (2008). Temperatures shown in black are calculated from EMPA data, and temperatures in gray are inferred (see text for discussion).

Fig. 5.

Paragenesis of minerals associated with retrograde metamorphism and weathering of basement rocks, diagenesis, and hydrothermal alteration. The 1757 Ma age of basement weathering is interpreted from Ar-Ar geochronology (see text for discussion), and the 1667 Ma age of early diagenesis is inferred from Davis et al. (2008). Temperatures shown in black are calculated from EMPA data, and temperatures in gray are inferred (see text for discussion).

Fig. 6.

Longitudinal sections of the F- and G-trends at Boomerang Lake, showing the distribution of peak diagenetic phyllosilicates (determined by SWIR spectrometry and XRD), and locations of samples with key geochemical and geochronological characteristics discussed in the text. Fmn. = Formation. Drill hole locations are shown in Figure 2.

Fig. 6.

Longitudinal sections of the F- and G-trends at Boomerang Lake, showing the distribution of peak diagenetic phyllosilicates (determined by SWIR spectrometry and XRD), and locations of samples with key geochemical and geochronological characteristics discussed in the text. Fmn. = Formation. Drill hole locations are shown in Figure 2.

Fig. 7.

a. Muscovite (M0) after biotite in F-trend paragneiss (sample BL92-47-213.2m; plane-polarized transmitted light). b. K0 kaolinite (K0) after biotite in F-trend paragneiss (sample BL92-41-122.4m; cross-polarized transmitted light). c. Hematite (F1) and euhedral Q1 quartz overgrowths mantle detrital Q0 quartz grains. Vivianite (P1a) fills primary porosity and is crosscut by K1 kaolinite. Late limonite stains all previous phases (sample BL06-65-116.3m; plane-polarized transmitted light). d. Fluorapatite (P1b) and M1 muscovite in sandstone interstices. The P1b fluorapatite displays hexagonal basal pinnacoid morphology. Both detrital Q0 quartz grains and P1b fluorapatite are partially dissolved in the presence of M1 muscovite (sample BL98-52-78.1m; SE-SEM image). e. Partially-dissolved P1b fluorapatite in contact with K1 kaolinite + M1 muscovite (sample BL98-52-78.1m; BSE-SEM image). f. Dolomite crosscuts P1b fluorapatite in F-trend basement paragneiss. Note extensively resorbed P1b grain boundaries (sample BL92-47-193.1m; cross-polarized transmitted light).

Fig. 7.

a. Muscovite (M0) after biotite in F-trend paragneiss (sample BL92-47-213.2m; plane-polarized transmitted light). b. K0 kaolinite (K0) after biotite in F-trend paragneiss (sample BL92-41-122.4m; cross-polarized transmitted light). c. Hematite (F1) and euhedral Q1 quartz overgrowths mantle detrital Q0 quartz grains. Vivianite (P1a) fills primary porosity and is crosscut by K1 kaolinite. Late limonite stains all previous phases (sample BL06-65-116.3m; plane-polarized transmitted light). d. Fluorapatite (P1b) and M1 muscovite in sandstone interstices. The P1b fluorapatite displays hexagonal basal pinnacoid morphology. Both detrital Q0 quartz grains and P1b fluorapatite are partially dissolved in the presence of M1 muscovite (sample BL98-52-78.1m; SE-SEM image). e. Partially-dissolved P1b fluorapatite in contact with K1 kaolinite + M1 muscovite (sample BL98-52-78.1m; BSE-SEM image). f. Dolomite crosscuts P1b fluorapatite in F-trend basement paragneiss. Note extensively resorbed P1b grain boundaries (sample BL92-47-193.1m; cross-polarized transmitted light).

Fig. 8.

a. Fluorapatite (P1b) crosscuts Q1 quartz overgrowths and is, in turn, crosscut by S1 pyrite. K1 kaolinite crosscuts S1 pyrite (sample BL07-70-210.8m; BSE-SEM image). b. Fine-grained K1 kaolinite is partially replaced by M1 muscovite. Coarser K2 dickite in the right half of the image is not replaced by M1 muscovite (sample JP-1-114.6m; cross-polarized transmitted light). c. and d. Tristramite (P2) in P1b fluorapatite + S1 pyrite + M1 muscovite-altered F-trend sandstone at the discovery zone. The P1b grain boundaries are extensively resorbed and in contact with M1 muscovite. The P2 tristramite is coincident with areas of increased S1 pyrite concentration (sample BL83-21-98.9m; BSE-SEM image). e. Hydrothermal siderite and Co + Ni arsenide in F-trend basement at the discovery zone (sample BL98-52-87.0m; BSE-SEM image). f. C2 sudoite replaces M1 muscovite in F-trend sandstone at the discovery zone (sample BL98-52-82.2m; BSE-SEM image).

Fig. 8.

a. Fluorapatite (P1b) crosscuts Q1 quartz overgrowths and is, in turn, crosscut by S1 pyrite. K1 kaolinite crosscuts S1 pyrite (sample BL07-70-210.8m; BSE-SEM image). b. Fine-grained K1 kaolinite is partially replaced by M1 muscovite. Coarser K2 dickite in the right half of the image is not replaced by M1 muscovite (sample JP-1-114.6m; cross-polarized transmitted light). c. and d. Tristramite (P2) in P1b fluorapatite + S1 pyrite + M1 muscovite-altered F-trend sandstone at the discovery zone. The P1b grain boundaries are extensively resorbed and in contact with M1 muscovite. The P2 tristramite is coincident with areas of increased S1 pyrite concentration (sample BL83-21-98.9m; BSE-SEM image). e. Hydrothermal siderite and Co + Ni arsenide in F-trend basement at the discovery zone (sample BL98-52-87.0m; BSE-SEM image). f. C2 sudoite replaces M1 muscovite in F-trend sandstone at the discovery zone (sample BL98-52-82.2m; BSE-SEM image).

Fig. 9.

Relationship between K and the degree of substitution for octahedral Al in white mica at Boomerang Lake, in reference to typical compositions of muscovite, illite, and aluminoceladonite reported by Deer et al. (1992). apfu = atoms per formula unit.

Fig. 9.

Relationship between K and the degree of substitution for octahedral Al in white mica at Boomerang Lake, in reference to typical compositions of muscovite, illite, and aluminoceladonite reported by Deer et al. (1992). apfu = atoms per formula unit.

Fig. 10.

Ternary diagram showing the chemical variation of chlorites at Boomerang Lake, in reference to the composition of relatively unaltered biotite in F-trend paragneiss at Boomerang Lake as determined by EMPA, typical compositions of chamosite and clinochlore reported by Deer et al. (1992), and sudoite reported by Lin and Bailey (1985).

Fig. 10.

Ternary diagram showing the chemical variation of chlorites at Boomerang Lake, in reference to the composition of relatively unaltered biotite in F-trend paragneiss at Boomerang Lake as determined by EMPA, typical compositions of chamosite and clinochlore reported by Deer et al. (1992), and sudoite reported by Lin and Bailey (1985).

Fig. 11.

a. Calculated (δ18O and (δ2H values of fluids in equilibrium with minerals at Boomerang Lake. Fields defining the range of calculated (δ18O and (δ2H values of fluids in equilibrium with sandstone-hosted kaolinite and dickite (a) and muscovite/illite and sudoite (b) in the Athabasca basin are plotted in gray for reference (MWL = meteoric water line, V-SMOW = Vienna Standard Mean Ocean Water). Sources of Athabasca data are Wilson and Kyser (1987), Kotzer (1993), Kotzer and Kyser (1995), Wasyliuk (2001), Alexandre et al. (2005), Cloutier (2009), and Cloutier et al. (2009). Athabasca δ18Ofluid and (δ18Hfluid values were calculated using temperatures suggested by the data authors, and fractionation factors presented in this paper for consistency. b. Plot of δ18Ofluid versus (δ13Cmineral compositions of carbonate minerals.

Fig. 11.

a. Calculated (δ18O and (δ2H values of fluids in equilibrium with minerals at Boomerang Lake. Fields defining the range of calculated (δ18O and (δ2H values of fluids in equilibrium with sandstone-hosted kaolinite and dickite (a) and muscovite/illite and sudoite (b) in the Athabasca basin are plotted in gray for reference (MWL = meteoric water line, V-SMOW = Vienna Standard Mean Ocean Water). Sources of Athabasca data are Wilson and Kyser (1987), Kotzer (1993), Kotzer and Kyser (1995), Wasyliuk (2001), Alexandre et al. (2005), Cloutier (2009), and Cloutier et al. (2009). Athabasca δ18Ofluid and (δ18Hfluid values were calculated using temperatures suggested by the data authors, and fractionation factors presented in this paper for consistency. b. Plot of δ18Ofluid versus (δ13Cmineral compositions of carbonate minerals.

Fig. 12.

The 40Ar/39Ar age spectra for three samples of sandstone-hosted Ml muscovite, one sample of basement-hosted Ml muscovite, and one sample of I0 illite from a basement fault zone.

Fig. 12.

The 40Ar/39Ar age spectra for three samples of sandstone-hosted Ml muscovite, one sample of basement-hosted Ml muscovite, and one sample of I0 illite from a basement fault zone.

Fig. 13.

a. Stratigraphic sections of selected drill holes on F-trend accompanied by plots of 207Pb/206Pb ratios. Drill hole BL98-52 intersects the discovery zone. b. Stratigraphic sections of selected drill holes on the G-trend accompanied by plots of 207Pb/206Pb ratios. See Holk et al. (2003) for similar plots from drill holes in the eastern Thelon, Athabasca and Kombolgie basins.

Fig. 13.

a. Stratigraphic sections of selected drill holes on F-trend accompanied by plots of 207Pb/206Pb ratios. Drill hole BL98-52 intersects the discovery zone. b. Stratigraphic sections of selected drill holes on the G-trend accompanied by plots of 207Pb/206Pb ratios. See Holk et al. (2003) for similar plots from drill holes in the eastern Thelon, Athabasca and Kombolgie basins.

Fig. 14.

Plot of 238U/206Pb versus 206Pb/204Pb for all samples at Boomerang Lake, showing the evolution of isotopic ratios from 250 Ma to 1750 Ma (Holk et al., 2003). Radiogenic Pb in all samples is supported by leachable U (indicative of Pb produced in situ) and plots outside the zone of unsupported Pb (hatched area) that is an indicator of a possible nearby uranium deposit.

Fig. 14.

Plot of 238U/206Pb versus 206Pb/204Pb for all samples at Boomerang Lake, showing the evolution of isotopic ratios from 250 Ma to 1750 Ma (Holk et al., 2003). Radiogenic Pb in all samples is supported by leachable U (indicative of Pb produced in situ) and plots outside the zone of unsupported Pb (hatched area) that is an indicator of a possible nearby uranium deposit.

Fig. 15.

Plot of 206Pb/204Pb versus 207Pb/204Pb for all samples at Boomerang Lake relative to the common Pb growth curve of Stacey and Kramers (1975). Most sandstone and basement samples from the F-and G-trends lie along a Pb-mixing isochron with an age of 1753 ±48 Ma. F- and G-trend sandstones that have experienced a lesser degree of diagenetic alteration lie along a Pb-mixing isochron with an age of 4909 ± 85 Ma.

Fig. 15.

Plot of 206Pb/204Pb versus 207Pb/204Pb for all samples at Boomerang Lake relative to the common Pb growth curve of Stacey and Kramers (1975). Most sandstone and basement samples from the F-and G-trends lie along a Pb-mixing isochron with an age of 1753 ±48 Ma. F- and G-trend sandstones that have experienced a lesser degree of diagenetic alteration lie along a Pb-mixing isochron with an age of 4909 ± 85 Ma.

Fig. 16.

Plot of 207Pb/206Pb ratios versus (Zr+Th)/U ratios for F- and G-trend samples. High (Zr+Th)/U ratios accompany all highly radiogenic samples, indicating a significant contribution of radiogenic Pb from accessory and detrital zircon and monazite. Decreasing (Zr+Th)/U ratios accompanied by decreasing 207Pb/206Pb ratios represent a prospective trend.

Fig. 16.

Plot of 207Pb/206Pb ratios versus (Zr+Th)/U ratios for F- and G-trend samples. High (Zr+Th)/U ratios accompany all highly radiogenic samples, indicating a significant contribution of radiogenic Pb from accessory and detrital zircon and monazite. Decreasing (Zr+Th)/U ratios accompanied by decreasing 207Pb/206Pb ratios represent a prospective trend.

Table 1.

Phases and Hosts of the S2 Assemblage

PhaseThelon Fmn. sandstoneBasement rocks
Unknown Co-Ni selenide
Unknown Co-As sulfide
Unknown Co-Ni arsenide
Ni-pyrite ("bravoite")
Unknown Ni-phosphide
Zn sulfide (sphalerite)
Unknown Cu-Zn
Cu sulfide (chalcopyrite)
Pb selenide ± Ag (clausthalite)
Pb sulfide (galena)
Unknown Bi selenide
Native Bi
PhaseThelon Fmn. sandstoneBasement rocks
Unknown Co-Ni selenide
Unknown Co-As sulfide
Unknown Co-Ni arsenide
Ni-pyrite ("bravoite")
Unknown Ni-phosphide
Zn sulfide (sphalerite)
Unknown Cu-Zn
Cu sulfide (chalcopyrite)
Pb selenide ± Ag (clausthalite)
Pb sulfide (galena)
Unknown Bi selenide
Native Bi
Table 2.

Representative Electron Microprobe Analyses of Phyllosilicates at Boomerang Lake

Sample123456789
Oxide (wt %)
SiO245.7652.6748.7247.2747.1858.4826.8732.0036.06
A2O332.4826.7633.7833.7617.7413.7217.9620.4832.43
FeO2.572.840.760.407.714.6030.3018.703.28
MnO0.030.02<DL0.020.070.020.06<DL<DL
MgO3.303.041.361.252.227.6711.4413.1014.51
TiO20.350.16<DL<DL0.02<DL0.130.04<DL
Cr2O3<DL<DL0.02<DL2.83<DL<DL0.020.04
V2O3n.a.n.a.0.02<DL2.10<DL0.05n.a.n.a.
BaOn.a.n.a.<DL0.130.12<DL<DLn.a.n.a.
CaO0.020.340.120.080.45<DL0.040.160.07
Na2O0.140.070.040.260.05<DL0.020.060.00
10.498.799.4210.334.0010.140.110.840.26
Cl0.020.05<DL<DL2.220.020.030.06<DL
F<DL0.540.40<DL0.200.400.040.11n.a.
O=Cl0.000.010.000.000.500.000.010.010.00
o=f0.000.230.170.000.080.170.020.040.00
TOTAL95.1795.0694.4893.4886.3394.9287.0285.5186.68
Atomic proportions
Number of oxygens222222222222282828
Tetrahedral Sites
Si6.026.416.346.305.806.394.766.576.55
AlIV1.981.591.661.702.201.613.241.431.45
Sum8.008.008.008.008.008.008.008.008.00
Octahedral sites
AlVI3.393.393.673.752.832.864.003.535.49
Fe0.280.290.080.040.790.424.493.210.50
Mn0.000.000.000.000.010.000.010.000.00
Mg0.650.550.260.250.411.253.024.013.93
Ti0.030.020.000.000.000.000.020.010.00
Sum4.354.254.014.044.044.5311.5410.769.92
Interlayer site
Ca0.000.040.020.010.060.000.010.040.01
Na0.040.020.010.070.010.000.010.020.00
K1.761.361.571.760.631.410.020.220.06
Sum1.801.421.601.840.701.410.040.280.07
Anions
Cl0.000.010.000.000.460.000.010.020.00
F0.000.210.170.000.080.140.020.070.00
OH4.003.783.834.003.463.8615.9715.9116.00
Temp. (°C)290210240260n.a.220340160190
Sample123456789
Oxide (wt %)
SiO245.7652.6748.7247.2747.1858.4826.8732.0036.06
A2O332.4826.7633.7833.7617.7413.7217.9620.4832.43
FeO2.572.840.760.407.714.6030.3018.703.28
MnO0.030.02<DL0.020.070.020.06<DL<DL
MgO3.303.041.361.252.227.6711.4413.1014.51
TiO20.350.16<DL<DL0.02<DL0.130.04<DL
Cr2O3<DL<DL0.02<DL2.83<DL<DL0.020.04
V2O3n.a.n.a.0.02<DL2.10<DL0.05n.a.n.a.
BaOn.a.n.a.<DL0.130.12<DL<DLn.a.n.a.
CaO0.020.340.120.080.45<DL0.040.160.07
Na2O0.140.070.040.260.05<DL0.020.060.00
10.498.799.4210.334.0010.140.110.840.26
Cl0.020.05<DL<DL2.220.020.030.06<DL
F<DL0.540.40<DL0.200.400.040.11n.a.
O=Cl0.000.010.000.000.500.000.010.010.00
o=f0.000.230.170.000.080.170.020.040.00
TOTAL95.1795.0694.4893.4886.3394.9287.0285.5186.68
Atomic proportions
Number of oxygens222222222222282828
Tetrahedral Sites
Si6.026.416.346.305.806.394.766.576.55
AlIV1.981.591.661.702.201.613.241.431.45
Sum8.008.008.008.008.008.008.008.008.00
Octahedral sites
AlVI3.393.393.673.752.832.864.003.535.49
Fe0.280.290.080.040.790.424.493.210.50
Mn0.000.000.000.000.010.000.010.000.00
Mg0.650.550.260.250.411.253.024.013.93
Ti0.030.020.000.000.000.000.020.010.00
Sum4.354.254.014.044.044.5311.5410.769.92
Interlayer site
Ca0.000.040.020.010.060.000.010.040.01
Na0.040.020.010.070.010.000.010.020.00
K1.761.361.571.760.631.410.020.220.06
Sum1.801.421.601.840.701.410.040.280.07
Anions
Cl0.000.010.000.000.460.000.010.020.00
F0.000.210.170.000.080.140.020.070.00
OH4.003.783.834.003.463.8615.9715.9116.00
Temp. (°C)290210240260n.a.220340160190

Notes: Phyllosilicate minerals with drill hole name and depth in parenthesis: 1 = M0 muscovite (BL06-65-240.2m), 2 = I0 illite (BL06-65-170.0m), 3 = M1 muscovite, Thelon Fmn.-sandstone-hosted (JP-2-231.2m); 4 = M1 muscovite, basement-rock-hosted (BL92-47-193.1m), 5 = M1 muscovite, Thelon Fmn.-sandstone-hosted, altered (BL83-21-98.9m), 6 = "aluminoceladonite" (BL98-52-84.0m), 7 = C0 chlorite (BL98-56-160.0m), 8 = C1 chlorite (BL92-47-193.1m), 9 = C2 sudoite (BL98-52-90.7m); atomic proportions calculated on an anhydrous basis, n.a. = not analyzed, <DL = below detection limit, OH calculated by subtraction; temperatures were calculated using the methods of Cathelineau (1988) and Zang and Fyfe (1995)

Table 3.

Kübler and Hinckley Indices of Phyllosilicates

Kübler Index (Kübler, 1967)
SampleMineralSize fractionHost rockKübler index
BL98-52-78.1mM1 muscovite<2Thelon Fmn. sandstone, discovery zone0.61
JP-2-219.6mM1 muscovite<2Thelon Fmn. sandstone0.66
JP-2-231.2mM1 muscovite<2Thelon Fmn. sandstone0.50
BL06-65-142.8mM1 muscovite<2 μmThelon Fmn. sandstone, near unconformity0.60
BL07-70-370.4mM1 muscovite<2Thelon Fmn. sandstone, near unconformity0.58
BL06-60-243.0mM1 muscovite<2Basement rocks, near unconformity0.27
BL06-65-222.4mM1 muscovite<2Basement rocks0.39
BL06-65-170.0m10 illite<2Basement rocks, fault zone0.95
Hinckley Index (Hinckley, 1963)
SampleMineralSize fractionHost rockHinckley index
BL07-69-55.0mK1 kaolinite<2 μmThelon Fmn. sandstone1.6
BL98-52-66.5mK1 kaolinite5-10Thelon Fmn. sandstone, discovery zone1.6
BL06-62-88.4mK1 kaolinite2-5Thelon Fmn. sandstone1.5
BL92-41-93.3mK0 kaolinitemBasement rocks1.1
BL06-64-99.2mK0 kaolinite2-5 μmBasement rocks1.2
BL83-22-114.0mK0 kaolinitemBasement rocks0.6
BL92-43-205.8mK0 kaolinitemBasement rocks0.6
BL07-69-272.9mK0 kaolinite2-5Basement rocks1.1
BL07-68-451.8mK0 kaolinitemBasement rocks, vein1.2
Kübler Index (Kübler, 1967)
SampleMineralSize fractionHost rockKübler index
BL98-52-78.1mM1 muscovite<2Thelon Fmn. sandstone, discovery zone0.61
JP-2-219.6mM1 muscovite<2Thelon Fmn. sandstone0.66
JP-2-231.2mM1 muscovite<2Thelon Fmn. sandstone0.50
BL06-65-142.8mM1 muscovite<2 μmThelon Fmn. sandstone, near unconformity0.60
BL07-70-370.4mM1 muscovite<2Thelon Fmn. sandstone, near unconformity0.58
BL06-60-243.0mM1 muscovite<2Basement rocks, near unconformity0.27
BL06-65-222.4mM1 muscovite<2Basement rocks0.39
BL06-65-170.0m10 illite<2Basement rocks, fault zone0.95
Hinckley Index (Hinckley, 1963)
SampleMineralSize fractionHost rockHinckley index
BL07-69-55.0mK1 kaolinite<2 μmThelon Fmn. sandstone1.6
BL98-52-66.5mK1 kaolinite5-10Thelon Fmn. sandstone, discovery zone1.6
BL06-62-88.4mK1 kaolinite2-5Thelon Fmn. sandstone1.5
BL92-41-93.3mK0 kaolinitemBasement rocks1.1
BL06-64-99.2mK0 kaolinite2-5 μmBasement rocks1.2
BL83-22-114.0mK0 kaolinitemBasement rocks0.6
BL92-43-205.8mK0 kaolinitemBasement rocks0.6
BL07-69-272.9mK0 kaolinite2-5Basement rocks1.1
BL07-68-451.8mK0 kaolinitemBasement rocks, vein1.2

Notes: m = mineral was sampled by microdrill

Table 4.

Representative Electron Microprobe Analyses of Phosphates At Boomerang Lake

Sample12
Oxide (wt %)
SrO0.060.82
CaO55.6913.74
Na2O<DL0.08
BaO<DL1.45
Y2O30.052.74
La2O30.040.12
Ce2O3<DL0.91
Pr2O3n.a.n.a.
Nd2O3<DL0.42
Sm2O30.060.17
UO2<DL35.18
ThO2n.a.n.a.
PbO2n.a.0.12
SiO2<DL0.13
Al2O3n.a.n.a.
FeO<DL2.36
MnO0.020.19
P2O541.9725.63
SO30.024.88
SeO4n.a.1.13
Cl0.020.07
F3.620.19
O=Cl0.000.02
O=F1.520.08
Total100.0189.11
Atomic proportions
number of oxygens124
Sr0.000.02
Ca4.640.57
ΣLREE0.000.02
Un.a.0.30
Thn.a.n.a.
Aln.a.n.a.
Fe0.000.08
P2.760.85
S0.000.14
F0.890.02
OH0.11*1.35
Sample12
Oxide (wt %)
SrO0.060.82
CaO55.6913.74
Na2O<DL0.08
BaO<DL1.45
Y2O30.052.74
La2O30.040.12
Ce2O3<DL0.91
Pr2O3n.a.n.a.
Nd2O3<DL0.42
Sm2O30.060.17
UO2<DL35.18
ThO2n.a.n.a.
PbO2n.a.0.12
SiO2<DL0.13
Al2O3n.a.n.a.
FeO<DL2.36
MnO0.020.19
P2O541.9725.63
SO30.024.88
SeO4n.a.1.13
Cl0.020.07
F3.620.19
O=Cl0.000.02
O=F1.520.08
Total100.0189.11
Atomic proportions
number of oxygens124
Sr0.000.02
Ca4.640.57
ΣLREE0.000.02
Un.a.0.30
Thn.a.n.a.
Aln.a.n.a.
Fe0.000.08
P2.760.85
S0.000.14
F0.890.02
OH0.11*1.35

Notes: Phosphate minerals with drill hole name and depth in parenthesis: 1 = P1b fluorapatite (BL07-70-210.8m); 2 = P2 tristramite (BL83-21-98.9m); atomic proportions calculated on an anhydrous basis; <DL = below detection limit; n.a. = not analyzed; * = expressed as H2O; OH and H2O calculated by subtraction

Table 5.

Oxygen, Hydrogen, and Carbon Stable Isotope Compositions of Alteration Phyllosilicates and Carbonates at Boomerang Lake

SampleLithologyMineralFraction sizeδ18OminδDminδ13CminH2O (%)Temp (°C)δ18OfluidδDfluid
Pre-Thelon basement paleosol
BL07-67-60.0mbsK0 kaolinite<2 μm9.3-608.92007.7-42
BL06-64-99.2mbsK0 kaolinite2-59.6-658.02008.0-48
BL07-69-272.9mbsK0 kaolinite2-511.8-6510.32008.2-47
BL07-68-451.8mbsK0 kaolinitem15.7-5516.120010.1-37
BL92-41-93.3mbsK0 kaolinitem14.6-6914.62009.0-52
BL83-22-114.0mbsK0 kaolinitem15.3-6413.9<50-4.4-35
BL92-43-205.8mbsK0 kaolinitem13.0-5712.2<50-6.7-28
BL06-65-170.0mbs10 illite<215.2-656.1<50-3.8-31
BL06-65-162.8mbsD0 dolomitem25.4-3<50-2.9
BL06-65-165.8mbsD0 dolomitem25.3-2.9<50-3.0
Peak diagenetic minerals
BL92-45-152.2mbsD1 dolomitem20.2-4.71305.1
BL92-47-193.1mbsD1 dolomitem25.0-10.61309.9
BL06-65-171.4mbsD1 dolomitem23.6-8.41308.4
BL07-69-55.0mssK1 kaolinite<214.4-6215.12008.8-44
BL06-62-88.4mssK1 kaolinite2-5 μm15.0-6113.12009.4-43
BL98-52-66.5mssK1 kaolinite5-1014.8-5614.32009.3-38
JP-2-219.6mssM1 muscovite<213.4-596.32508.6-25
JP-2-231.2mssM1 muscovite<213.2-636.02508.4-29
BL07-70-370.0mssM1 muscovite<212.4-586.62507.6-24
BL98-52-78.1mssM1 muscovite<2 μm13.8-646.02508.9-30
BL06-65-142.8mssM1 muscovite<212.5-677.12507.7-33
BL07-69-74.9mssK2 dickite5-1010.0-5313.92506.7-37
BL07-69-84.8mssK2 dickite5-10 μm11.3-5813.42508.0-43
BL07-68-198.1mssK2 dickite5-1011.2-4713.52507.9-31
BL91-35-77.9mssK2 dickite5-10 μm10.4-6010.92507.0-45
BL92-50-130.3mssK2 dickite5-1010.2-5411.32506.8-38
Th08-1ssK2 dickite2-512.6-9210.42509.2-76
Th08-6ssK2 dickite2-5 μm12.2-8211.02508.9-67
Th08-8ssK2 dickite2-511.6-7211.52508.2-56
BL07-67-53.4mssK2 dickitem8.2-5215.82504.8-36
BL07-70-130.3mssK2 dickitem7.6-5215.62504.3-36
BL07-69-240.3mssK2 dickitem8.9-5414.62505.6-39
BL07-69.264.2mssK2 dickitem7.7-5015.02504.4-35
Hydrothermalalteration
BL98-52-87.0mbssideritem22.1-14.520011.1
JP-1-260.5mssC2 sudoite<2 μm11.8-5910.22009.6-25
JP-4-209.0mssC2 sudoite<211.4-5611.22009.1-22
JP-4-232.6mssC2 sudoite<211.6-5410.32009.3-20
JP-4-255.5mssC2 sudoite<210.3-5212.22008.0-18
BL07-70-378.9mssC2 sudoite<211.3-5612.72009.0-22
BL83-22-93.3mssC2 sudoite<2 μm12.5-5911.020010.2-25
BL06-61-190.7mssC2 sudoite<211.6-5511.92009.3-21
SampleLithologyMineralFraction sizeδ18OminδDminδ13CminH2O (%)Temp (°C)δ18OfluidδDfluid
Pre-Thelon basement paleosol
BL07-67-60.0mbsK0 kaolinite<2 μm9.3-608.92007.7-42
BL06-64-99.2mbsK0 kaolinite2-59.6-658.02008.0-48
BL07-69-272.9mbsK0 kaolinite2-511.8-6510.32008.2-47
BL07-68-451.8mbsK0 kaolinitem15.7-5516.120010.1-37
BL92-41-93.3mbsK0 kaolinitem14.6-6914.62009.0-52
BL83-22-114.0mbsK0 kaolinitem15.3-6413.9<50-4.4-35
BL92-43-205.8mbsK0 kaolinitem13.0-5712.2<50-6.7-28
BL06-65-170.0mbs10 illite<215.2-656.1<50-3.8-31
BL06-65-162.8mbsD0 dolomitem25.4-3<50-2.9
BL06-65-165.8mbsD0 dolomitem25.3-2.9<50-3.0
Peak diagenetic minerals
BL92-45-152.2mbsD1 dolomitem20.2-4.71305.1
BL92-47-193.1mbsD1 dolomitem25.0-10.61309.9
BL06-65-171.4mbsD1 dolomitem23.6-8.41308.4
BL07-69-55.0mssK1 kaolinite<214.4-6215.12008.8-44
BL06-62-88.4mssK1 kaolinite2-5 μm15.0-6113.12009.4-43
BL98-52-66.5mssK1 kaolinite5-1014.8-5614.32009.3-38
JP-2-219.6mssM1 muscovite<213.4-596.32508.6-25
JP-2-231.2mssM1 muscovite<213.2-636.02508.4-29
BL07-70-370.0mssM1 muscovite<212.4-586.62507.6-24
BL98-52-78.1mssM1 muscovite<2 μm13.8-646.02508.9-30
BL06-65-142.8mssM1 muscovite<212.5-677.12507.7-33
BL07-69-74.9mssK2 dickite5-1010.0-5313.92506.7-37
BL07-69-84.8mssK2 dickite5-10 μm11.3-5813.42508.0-43
BL07-68-198.1mssK2 dickite5-1011.2-4713.52507.9-31
BL91-35-77.9mssK2 dickite5-10 μm10.4-6010.92507.0-45
BL92-50-130.3mssK2 dickite5-1010.2-5411.32506.8-38
Th08-1ssK2 dickite2-512.6-9210.42509.2-76
Th08-6ssK2 dickite2-5 μm12.2-8211.02508.9-67
Th08-8ssK2 dickite2-511.6-7211.52508.2-56
BL07-67-53.4mssK2 dickitem8.2-5215.82504.8-36
BL07-70-130.3mssK2 dickitem7.6-5215.62504.3-36
BL07-69-240.3mssK2 dickitem8.9-5414.62505.6-39
BL07-69.264.2mssK2 dickitem7.7-5015.02504.4-35
Hydrothermalalteration
BL98-52-87.0mbssideritem22.1-14.520011.1
JP-1-260.5mssC2 sudoite<2 μm11.8-5910.22009.6-25
JP-4-209.0mssC2 sudoite<211.4-5611.22009.1-22
JP-4-232.6mssC2 sudoite<211.6-5410.32009.3-20
JP-4-255.5mssC2 sudoite<210.3-5212.22008.0-18
BL07-70-378.9mssC2 sudoite<211.3-5612.72009.0-22
BL83-22-93.3mssC2 sudoite<2 μm12.5-5911.020010.2-25
BL06-61-190.7mssC2 sudoite<211.6-5511.92009.3-21

Notes: Temperatures of white mica and chlorite were calculated using mineral chemistry and the methods of Cathelineau (1988) and Zang and Fyfe (1995); temperatures used for kaolin and carbonate minerals are discussed in the text; bs = basement rocks; ss = Thelon Formation sandstone; m = sampled by microdrill; oxygen and hydrogen isotope ratios are in units of per mil relative to V-SMOW; carbon isotope ratios are in units of per mil relative to PDB

Table 6.

40Ar/39Ar Analytical Data for I0 Illite and M1 Muscovite

Step36Ar/40Ar39Ar/40ArCa/K40Ar air (%)39Ar (%)40Ar*/39ArKAge (Ma)± 2σStep36Ar/40Ar39Ar/40ArCa/K40Ar air (%)39Ar (%)40Ar*/39ArKAge (Ma)± 2σ
BL06-65-142.8m (Thelon Fmn. sandstone, near unconformity), plateau age = 1337 ±4 MaBL06-60-243.0m (basement rocks, near unconformity), pseudo-plateau age = 1752 ±19 Ma
10.00010.02030.0096.71.647.6712547510.00000.01450.1599.19.368.38160856
20.00010.018397.68.053.2413561520.00000.01360.0698.918.872.69167433
30.00000.02010.0399.011.349.3012841230.00000.01270.0498.714.377.95175135
40.00000.01920.02100.09.552.0013341040.00010.01260.0597.613.877.64174747
50.00000.01910.0299.510.752.2313381450.00010.01270.0698.511.277.77174943
60.00000.01910.0499.717.952.321340860.00010.01250.0698.09.978.64176147
70.00000.01910.0099.826.852.201337670.00000.01270.1299.38.978.06175355
80.00000.01930.01100.012.751.921332980.00000.01250.3599.43.779.361772134
90.00000.02890.01100.00.634.5898718290.00020.01770.4495.210.253.83136649
100.00030.01940.2490.60.946.791237133
BL98-52-78.1m (Thelon Fmn. sandstone, discovery zone), pseudo-plateau age = 1302 ±11 MaBL06-60-243.0m (duplicate), plateau age = 1738 ±14 Ma
10.00000.02340.9399.93.842.7411578210.00080.012676.80.360.7914861257
20.00000.02200.8698.622.144.9012001420.00000.015099.711.466.30157639
30.00000.02070.78100.014.448.3212652430.00000.01310.0499.623.976.17172619
40.00000.01990.80100.022.650.1613001540.00000.01300.0199.516.676.46173022
50.00000.01960.8399.417.750.6013081950.00000.01270.0399.912.078.39175833
60.00000.01971.07100.08.950.7013104060.00000.01290.0399.58.777.16174050
70.00000.02162.0899.84.446.31122710770.00000.01260.0199.27.179.01176759
80.00010.03857.2098.23.925.4977514280.00000.01260.0099.013.978.82176430
90.00000.108150.2699.42.49.2031917590.00010.01340.0297.96.172.86167770
JP-2-219.6m (Thelon Fmn. sandstone), plateau age = 1339 ±6 MaBL06-65-170.0m (basement rocks, fault zone), pseudo-plateau age = 1758 ±7 Ma
10.00000.01990.0098.65.549.4812884310.00000.014098.83.170.76164592
20.00000.01950.0299.710.051.1913192320.00000.01310.0699.023.975.35171415
30.00000.01920.0399.56.951.9313333730.00000.01270.0099.320.278.29175611
40.00000.01910.0399.511.052.0313342240.00000.01260.0499.313.778.82176410
50.00000.01910.0399.512.352.1713372050.00010.01260.0998.49.177.90175115
60.00000.01900.0399.416.352.4513421560.00000.01330.0699.111.374.80170613
70.00000.01900.0099.829.452.511343970.00000.01340.0299.815.174.52170115
80.00030.02480.6891.28.636.8110356180.00000.01440.1398.73.568.80161540
Step36Ar/40Ar39Ar/40ArCa/K40Ar air (%)39Ar (%)40Ar*/39ArKAge (Ma)± 2σStep36Ar/40Ar39Ar/40ArCa/K40Ar air (%)39Ar (%)40Ar*/39ArKAge (Ma)± 2σ
BL06-65-142.8m (Thelon Fmn. sandstone, near unconformity), plateau age = 1337 ±4 MaBL06-60-243.0m (basement rocks, near unconformity), pseudo-plateau age = 1752 ±19 Ma
10.00010.02030.0096.71.647.6712547510.00000.01450.1599.19.368.38160856
20.00010.018397.68.053.2413561520.00000.01360.0698.918.872.69167433
30.00000.02010.0399.011.349.3012841230.00000.01270.0498.714.377.95175135
40.00000.01920.02100.09.552.0013341040.00010.01260.0597.613.877.64174747
50.00000.01910.0299.510.752.2313381450.00010.01270.0698.511.277.77174943
60.00000.01910.0499.717.952.321340860.00010.01250.0698.09.978.64176147
70.00000.01910.0099.826.852.201337670.00000.01270.1299.38.978.06175355
80.00000.01930.01100.012.751.921332980.00000.01250.3599.43.779.361772134
90.00000.02890.01100.00.634.5898718290.00020.01770.4495.210.253.83136649
100.00030.01940.2490.60.946.791237133
BL98-52-78.1m (Thelon Fmn. sandstone, discovery zone), pseudo-plateau age = 1302 ±11 MaBL06-60-243.0m (duplicate), plateau age = 1738 ±14 Ma
10.00000.02340.9399.93.842.7411578210.00080.012676.80.360.7914861257
20.00000.02200.8698.622.144.9012001420.00000.015099.711.466.30157639
30.00000.02070.78100.014.448.3212652430.00000.01310.0499.623.976.17172619
40.00000.01990.80100.022.650.1613001540.00000.01300.0199.516.676.46173022
50.00000.01960.8399.417.750.6013081950.00000.01270.0399.912.078.39175833
60.00000.01971.07100.08.950.7013104060.00000.01290.0399.58.777.16174050
70.00000.02162.0899.84.446.31122710770.00000.01260.0199.27.179.01176759
80.00010.03857.2098.23.925.4977514280.00000.01260.0099.013.978.82176430
90.00000.108150.2699.42.49.2031917590.00010.01340.0297.96.172.86167770
JP-2-219.6m (Thelon Fmn. sandstone), plateau age = 1339 ±6 MaBL06-65-170.0m (basement rocks, fault zone), pseudo-plateau age = 1758 ±7 Ma
10.00000.01990.0098.65.549.4812884310.00000.014098.83.170.76164592
20.00000.01950.0299.710.051.1913192320.00000.01310.0699.023.975.35171415
30.00000.01920.0399.56.951.9313333730.00000.01270.0099.320.278.29175611
40.00000.01910.0399.511.052.0313342240.00000.01260.0499.313.778.82176410
50.00000.01910.0399.512.352.1713372050.00010.01260.0998.49.177.90175115
60.00000.01900.0399.416.352.4513421560.00000.01330.0699.111.374.80170613
70.00000.01900.0099.829.452.511343970.00000.01340.0299.815.174.52170115
80.00030.02480.6891.28.636.8110356180.00000.01440.1398.73.568.80161540

Notes: ✓ = step used in calculation of weighted plateau and pseudoplateau age

Table 7.

U and Pb Isotope Ratios and Selected Elemental Concentrations of Weak Acid Leachates from Boomerang Lake

Sample no.Lith.Location206Pb/204Pb207Pb/204Pb207Pb/206Pb238U/206PbP (ppb)V (ppb)Co (ppb)Ni (ppb)Cu (ppb)Zn (ppb)As (ppb)Zr (ppb)Ce (ppb)Th (ppb)U (ppb)
BL83-22-61.0ssF-trend22.318.00.812.268090<DL<DL680210<DL160<DL<DL70
BL83-22-68.8ssF-trend21.417.10.801.6128070<DL<DL740270<DL380<DL<DL<DL
BL83-22-91.0ssF-trend29.717.40.59317.0647070<DL501760360140290<DL<DL2460
BL83-22-93.3ssF-trend32.016.30.51231.599901030<DL350205016404202009015019000
BL83-22-94.4pgnF-trend24.416.30.672.6460007030426019806804550602001560470770
BL83-22-98.0pgnF-trend28.816.90.580.516000135092023905602960<DL3002040130<DL
BL83-22-104.5pgnF-trend23.816.20.681.3619020907004404801330<DL4701890210500
BL83-22-111.1pgnF-trend21.715.90.731.01090380<DL100570560<DL840830810280
BL83-22-114.0pgnF-trend20.916.00.772.0161024010706407980600<DL168045013201290
BL98-52-66.5ssF-trend18.015.50.8611.12670480<DL507301010<DL11060<DL200
BL98-52-70.3ssF-trend19.917.20.874.42500<DL<DL50740380<DL100<DL<DL70
BL98-52-75.3ssF-trend24.316.70.698.219000080<DL190710320150250430350720
BL98-52-78.1ssF-trend26.417.00.640.52200000270<DL704002300230166011801901520
BL98-52-82.2ssF-trend21.115.90.7527.841702807005801420240200<DL<DL<DL1840
BL98-52-83.6pgnF-trend31.816.90.5310.81800000400060000270003100031000250007802970170023000
BL98-52-87.0pgnF-trend27.816.40.595.7450000394029000037000073803200047000042085609405180
BL98-52-88.8pgnF-trend27.716.50.60155.71000001000057000028000013000210008200004103700056309300
BL98-52-90.7pgnF-trend32.217.70.5512.094504003360222029904270140110840140440
BL98-52-92.6pgnF-trend33.318.10.5430.2803101960133010202160<DL<DL76080640
BL98-56-78.3ssF-trend26.121.80.849.6n.a.n.a.9040700830302502010140
BL98-56-100.7ssF-trend18.615.40.8256.3n.a.n.a.28012011804050406040201310
BL98-56-102.8pgnF-trend30.116.60.554.7110001880<DL9004201500<DL2501930230390
BL98-56-160.0pgnF-trend32.217.40.545.1170000250<DL<DL460810<DL603380<DL240
BL92-41-79.5ssF-trend22.316.20.735.42200070<DL<DL950630<DL150120180220
BL92-41-122.4pgnF-trend30.117.10.571.238000<DL<DL<DL<DL2540<DL<DL2280100170
BL92-41-165.9pgnF-trend27.716.80.600.9460000<DL<DL<DL7201600<DL<DL2320<DL240
BL98-58-136.7pgnF-trend33.017.00.527.496039804810<DL6709930460<DL21409805960
BL98-58-138.2pgnF-trend20.815.80.761.71600057802150<DL1840383060<DL1100250350
BL98-58-143.9pgnF-trend20.415.90.782.021002660<DL<DL3540870<DL<DL298023001050
BL98-58-155.0pgnF-trend22.115.80.711.8120001160<DL<DL<DL870<DL<DL2810310280
BL98-58-178.3pgnF-trend40.418.20.452.9240000<DL<DL<DL<DL1360<DL<DL3020120180
BL91-34-148.2ssF-trend25.320.30.800.6179060<DL<DL920560<DL150240<DL<DL
BL91-34-154.1pgnF-trend28.917.00.5912.5139041208101320700285011014010403902060
BL91-34-169.1pgnF-trend23.516.40.702.957301010430194014801700<DL58018507405050
BL06-61-97.5ssF-trend24.119.50.813.73030100400<DL1210370<DL<DL<DL<DL100
BL06-61-100.3ssF-trend20.016.60.830.6192070410<DL1830650<DL<DL<DL<DL50
BL06-61-108.8ssF-trend28.523.70.837.82510<DL740<DL650260<DL<DL<DL<DL130
BL06-61-117.0ssF-trend25.521.10.831.52120<DL260<DL860240<DL<DL<DL<DL<DL
BL06-61-121.7ssF-trend28.023.80.853.13500<DL140<DL530200<DL<DL<DL<DL<DL
BL06-61-127.6ssF-trend32.225.50.7928.41800090270<DL610370<DL<DL120<DL290
BL06-61-135.0ssF-trend27.223.30.862.63380<DL610<DL770510<DL<DL<DL<DL<DL
BL06-61-144.0ssF-trend22.819.90.871.64850<DL790<DL1340390<DL<DL<DL<DL<DL
BL06-61-147.5ssF-trend33.627.70.831.24220<DL780<DL980610<DL<DL<DL<DL<DL
BL06-61-156.0ssF-trend23.718.50.780.91610<DL270<DL850260<DL<DL<DL<DL<DL
BL06-61-165.0ssF-trend25.118.60.740.41920<DL330<DL520170<DL<DL<DL<DL<DL
BL06-61-169.5ssF-trend24.219.20.791.61820<DL370<DL620460<DL<DL160<DL<DL
BL06-61-176.5ssF-trend24.917.30.702.02230<DL1205054036090<DL410<DL80
BL06-61-186.2ssF-trend68.121.00.313.44300000490190210530310850125024802703190
BL06-61-187.6ssF-trend49.521.10.432.212000013015070570260801101280210230
BL06-61-190.7ssF-trend26.516.60.624.2100000270370<DL790620<DL130260<DL630
BL06-61-199.1pgnF-trend67.021.50.328.5n.a.n.a.25024043047011012031803301220
BL06-61-208.8pgnF-trend27.817.40.639.6n.a.n.a.50067064014701001802500400820
BL06-61-225.7pgnF-trend18.416.90.920.6n.a.n.a.220280460870<DL605110650200
BL06-61-237.6pgnF-trend24.215.80.6511.5n.a.n.a.320130064035907030519012101130
BL91-38-253.8pgnF-trend35.317.60.503.1n.a.n.a.19017057025501802003190350390
BL91-38-260.8pgnF-trend70.421.20.303.0n.a.n.a.ll012087027002403002330240450
BL06-60-104.5ssF-trend2l.l16.00.751.1n.a.n.a.26050350220<DL60704060
BL06-60-233.7ssF-trend24.218.00.7438.6n.a.n.a.430902802260<DL4014040310
BL06-60-235.2pgnF-trend51.7l9.l0.374.6n.a.n.a.6105702803220ll03904590740530
BL06-60-244.0pgnF-trend38.117.30.467.7n.a.n.a.1808208909901002005670950360
BL92-45-107.2ssF-trend20.216.40.811.1n.a.n.a.<DL<DL920460<DL<DL10<DL30
BL92-45-119.3ssF-trend19.516.50.852.2n.a.n.a.<DL<DL690740<DL<DL10<DL50
BL92-45-129.5ssF-trend20.216.00.794.9n.a.n.a.7030970620<DL<DL<DL<DL130
BL92-45-136.8ssF-trend22.117.30.780.9n.a.n.a.<DL<DL91085030<DL2010<DL
BL92-45-138.0pgnF-trend25.116.80.6718.2n.a.n.a.<DL100510122040<DL230130690
BL92-45-142.0pgnF-trend40.7l9.l0.4734.5n.a.n.a.<DL140780310050<DL16401601800
BL92-45-152.2pgnF-trend269.342.30.168.0n.a.n.a.271028201510307025041023704606020
BL92-43-86.9ssF-trend20.4l6.l0.791.2n.a.n.a.10030830960<DL140202030
BL92-43-96.3ssF-trend29.222.10.760.7n.a.n.a.10030179064040<DL201030
BL92-43-110.9ssF-trend18.615.00.810.7n.a.n.a.ll03012l01070807010080
BL92-43-122.4ssF-trend20.716.40.793.8n.a.n.a.14060800700404013040ll0
BL92-43-123.8ssF-trend19.815.50.780.7n.a.n.a.ll0<DL10801080<DL160<DL<DL<DL
BL92-43-133.0ssF-trend282.640.70.144.3n.a.n.a.12017010108701170153017402307920
BL92-43-147.0pgnF-trend26.816.20.619.2n.a.n.a.2305107901760ll0<DL2100190620
BL92-43-173.8pgnF-trend45.418.30.403.4n.a.n.a.25072063059601402605830270460
BL92-43-189.8pgnF-trend34.7l7.l0.492.3n.a.n.a.8502600108051001701702480100380
BL92-43-205.9pgnF-trend43.019.20.453.2n.a.n.a.360790109028001701903140130330
BL06-65-69.4ssF-trend29.823.40.791.6n.a.n.a.310405005804020302020
BL06-65-87.4ssF-trend*0.665.3n.a.n.a.12208086061040<DL101060
BL06-65-99.4ssF-trend19.315.50.812.3n.a.n.a.2504097056030<DL20<DL70
BL06-65-111.7ssF-trendl9.ll5.l0.7912.7n.a.n.a.150<DL5702630<DL30<DL<DL120
BL06-65-123.7ssF-trend23.318.70.8010.4n.a.n.a.1903058054030101010170
BL06-65-132.5ssF-trend69.820.40.293.9n.a.n.a.330704201800600144031205702960
BL06-65-142.9ssF-trend**0.6912.4n.a.n.a.4205024030060<DLll04040
BL06-65-144.3pgnF-trend28.615.70.550.8n.a.n.a.1508073079090<DL138012040
BL06-65-147.3pgnF-trend32.616.80.524.2n.a.n.a.17070260310210<DL195078090
BL06-65-162.8pgnF-trend39.617.50.4426.0n.a.n.a.9750430182077012060400050700
BL06-65-170.0pgnF-trend63.120.90.3334.2n.a.n.a.130ll06304502508014000330920
BL06-65-177.3pgnF-trend30.316.60.550.8n.a.n.a.12l08201970650330<DL96020100
BL06-65-198.6pgnF-trend31.617.30.550.4n.a.n.a.650390500900ll030770<DL<DL
BL06-65-222.4pgnF-trend36.216.80.460.6n.a.n.a.61304120185024408403906090760570
BL92-47-124.0ssF-trend25.520.00.7824.3n.a.n.a.190801990175060<DL3040370
BL92-48-110.2ssF-trend24.517.90.732.0n.a.n.a.904012l0540<DL<DL1205050
BL92-48-202.1ssF-trend22.217.20.780.8n.a.n.a.100408702530605402507060
BL92-50-244.1ssF-trend21.4l6.l0.7517.0n.a.n.a.9010062098040<DL330120680
BL92-50-250.0pgnF-trend31.017.00.554.3n.a.n.a.491069902900011904602204400024905160
BL92-50-270.8pgnF-trend31.717.50.556.0n.a.n.a.389063001000022801160170850012401420
BL92-50-280.1pgnF-trend30.616.80.551.4n.a.n.a.2080243013702260230<DL50406501130
BL07-67-43.7ssG-trendll3.225.40.226.4n.a.n.a.ll021062010305102210610010503260
BL07-67-57.6ssG-trend24.816.20.652.5n.a.n.a.3906507903030400140720320270
BL07-67-60.0ggnG-trend26.316.40.622.6n.a.n.a.50709509908080510650410
BL07-67-187.3ggnG-trend52.4l8.l0.3410.3n.a.n.a.300501060690250ll01500018504170
BL07-67-230.2qmsG-trend22.315.90.719.9n.a.n.a.2040690630130501850360530
BL06-64-52.4ssG-trend61.920.00.32366.3n.a.n.a.1330235082015000100056012l066024000
BL06-64-80.2ssG-trend29.220.90.7213.0n.a.n.a.21017010706250<DL<DL15050250
BL06-64-93.5ssG-trend32.820.60.633.0n.a.n.a.50ll0790330<DL305050100
BL06-64-98.0ssG-trend25.816.70.65ll.3n.a.n.a.4605206101140905038050420
BL06-64-111.3ggnG-trend21.415.90.742.0n.a.n.a.40<DL710490ll0402320590100
BL06-62-88.4ssG-trend22.516.20.725.0n.a.n.a.5040750390<DL10013060200
BL06-62-116.6ssG-trend20.815.90.7612.9n.a.n.a.3101808602960<DL280ll080640
BL06-62-155.8ssG-trend31.516.90.546.1n.a.n.a.8014069050011010027050310
BL06-62-220.9qmsG-trend25.116.30.653.4n.a.n.a.13018077054026030950770210
BL06-62-252.2qmsG-trend25.416.40.655.5n.a.n.a.4080580190120401680490250
BL06-63-250.3ssG-trend25.716.50.641.1n.a.n.a.20<DL810470<DL30301090
BL06-63-300.2ssG-trend22.116.10.730.3n.a.n.a.105093034012090702020
BL06-63-315.5ssG-trend23.016.20.711.1n.a.n.a.210150600530220401703050
BL06-63-318.1qmsG-trend21.916.20.746.5n.a.n.a.9020094031038020320220240
BL07-69-55.0ssG-trend18.915.40.828.6n.a.n.a.20<DL840310<DL70180100180
BL07-69-84.8ssG-trend17.815.10.853.1n.a.n.a.10<DL830190<DL30302050
BL07-69-126.1ssG-trend20.215.60.777.5n.a.n.a.10101020360<DL404040200
BL07-69-165.1ssG-trend18.815.50.826.3n.a.n.a.0<DL6802301040302090
BL07-69-205.0ssG-trend25.016.60.667.6n.a.n.a.1040135026060703030200
BL07-69-230.2ssG-trend35.317.30.495.5n.a.n.a.601007203901901301150200220
BL07-69-239.7ssG-trend19.515.50.790.3n.a.n.a.2040101042090100870390520
BL07-69-250.2ssG-trend55.119.50.354.8n.a.n.a.10309805801102071025060
BL07-69-256.2ssG-trend19.315.40.800.7n.a.n.a.80<DL6309003401305670270250
BL07-69-261.9ssG-trend35.418.20.529.2n.a.n.a.40<DL8104102101201230210220
BL07-69-266.0ggnG-trend26.416.30.625.9n.a.n.a.20401070440130110910420550
BL07-69-272.9ggnG-trend20.015.60.781.4n.a.n.a.10309505301003065024050
BL07-69-285.9ggnG-trend19.715.60.792.0n.a.n.a.6060730120038080885037080
BL07-69-311.5ggnG-trend37.517.80.483.2n.a.n.a.80606808903001305720280260
BL07-69-337.4ggnG-trend31.517.20.551.8n.a.n.a.1101106307608090315026090
BL07-69-343.1qmsG-trend128.627.40.215.8n.a.n.a.60130102057062031017704901500
BL07-69-356.3qmsG-trend31.116.80.543.5n.a.n.a.5060530210180301880700220
BL07-69-377.9qmsG-trend36.617.30.4718.9n.a.n.a.4090560450140301020510860
BL07-69-393.3qmsG-trend20.416.00.780.8n.a.n.a.305045026080301120280230
BL07-68-118.2ssG-trend21.616.00.741.2n.a.n.a.2030102016405028014060110
BL07-68-238.1ssG-trend21.215.90.754.8n.a.n.a.3070840500<DL150170120240
BL07-68-417.5ssG-trend173.631.80.184.5n.a.n.a.1040380290330137010103301610
BL07-68-431.4qmsG-trend24.316.40.670.7n.a.n.a.2020580140609044011030
BL07-70-40.4ssG-trend20.616.10.783.6n.a.n.a.80<DL910390<DL1307030220
BL07-70-71.1ssG-trend22.116.30.741.2n.a.n.a.70<DL80049040280470220240
BL07-70-101.1ssG-trend25.016.80.671.7n.a.n.a.702098035040130190140460
BL07-70-130.3ssG-trend30.018.40.616.2n.a.n.a.11014069052070<DL200170650
BL07-70-160.2ssG-trend49.719.30.393.7n.a.n.a.330280490800170146016009801450
BL07-70-190.1ssG-trend24.917.60.711.6n.a.n.a.6030550320<DL<DL404050
BL07-70-210.8ssG-trend70.921.10.303.8n.a.n.a.7409201810103017102840467015006460
BL07-70-215.1ssG-trend23.816.40.690.4n.a.n.a.201708302501603072020020
BL07-70-220.6ssG-trend22.117.50.791.8n.a.n.a.70<DL390320100<DL1806090
BL07-70-250.9ssG-trend21.216.60.781.7n.a.n.a.602094024010050<DL8080
BL07-70-280.0ssG-trend24.017.80.740.3n.a.n.a.6040620460<DL40807020
BL07-70-310.1ssG-trend109.126.30.244.0n.a.n.a.140430260320310136029507102060
BL07-70-339.9ssG-trend20.316.50.810.8n.a.n.a.903085069030<DL24014070
BL07-70-360.4ssG-trend26.717.10.643.3n.a.n.a.703010002406040110120190
BL07-70-370.4ssG-trend260.241.80.164.1n.a.n.a.24029083026088099021003404870
BL07-70-378.9ssG-trend29.218.20.622.3n.a.n.a.250606302406011060110120
BL07-70-386.5qmsG-trend43.018.30.431.4n.a.n.a.170170400370990602905001010
BL07-70-391.3qmsG-trend34.418.50.548.3n.a.n.a.9012066015903105018801020700
BL07-70-410.0qmsG-trend59.019.40.3313.3n.a.n.a.130120720340350150410016602360
BL07-70-433.3qmsG-trend21.616.20.751.5n.a.n.a.6302101150840330210250001890770
BL07-70-447.7qmsG-trend57.720.40.355.3n.a.n.a.1802206706304402001100015501110
Sample no.Lith.Location206Pb/204Pb207Pb/204Pb207Pb/206Pb238U/206PbP (ppb)V (ppb)Co (ppb)Ni (ppb)Cu (ppb)Zn (ppb)As (ppb)Zr (ppb)Ce (ppb)Th (ppb)U (ppb)
BL83-22-61.0ssF-trend22.318.00.812.268090<DL<DL680210<DL160<DL<DL70
BL83-22-68.8ssF-trend21.417.10.801.6128070<DL<DL740270<DL380<DL<DL<DL
BL83-22-91.0ssF-trend29.717.40.59317.0647070<DL501760360140290<DL<DL2460
BL83-22-93.3ssF-trend32.016.30.51231.599901030<DL350205016404202009015019000
BL83-22-94.4pgnF-trend24.416.30.672.6460007030426019806804550602001560470770
BL83-22-98.0pgnF-trend28.816.90.580.516000135092023905602960<DL3002040130<DL
BL83-22-104.5pgnF-trend23.816.20.681.3619020907004404801330<DL4701890210500
BL83-22-111.1pgnF-trend21.715.90.731.01090380<DL100570560<DL840830810280
BL83-22-114.0pgnF-trend20.916.00.772.0161024010706407980600<DL168045013201290
BL98-52-66.5ssF-trend18.015.50.8611.12670480<DL507301010<DL11060<DL200
BL98-52-70.3ssF-trend19.917.20.874.42500<DL<DL50740380<DL100<DL<DL70
BL98-52-75.3ssF-trend24.316.70.698.219000080<DL190710320150250430350720
BL98-52-78.1ssF-trend26.417.00.640.52200000270<DL704002300230166011801901520
BL98-52-82.2ssF-trend21.115.90.7527.841702807005801420240200<DL<DL<DL1840
BL98-52-83.6pgnF-trend31.816.90.5310.81800000400060000270003100031000250007802970170023000
BL98-52-87.0pgnF-trend27.816.40.595.7450000394029000037000073803200047000042085609405180
BL98-52-88.8pgnF-trend27.716.50.60155.71000001000057000028000013000210008200004103700056309300
BL98-52-90.7pgnF-trend32.217.70.5512.094504003360222029904270140110840140440
BL98-52-92.6pgnF-trend33.318.10.5430.2803101960133010202160<DL<DL76080640
BL98-56-78.3ssF-trend26.121.80.849.6n.a.n.a.9040700830302502010140
BL98-56-100.7ssF-trend18.615.40.8256.3n.a.n.a.28012011804050406040201310
BL98-56-102.8pgnF-trend30.116.60.554.7110001880<DL9004201500<DL2501930230390
BL98-56-160.0pgnF-trend32.217.40.545.1170000250<DL<DL460810<DL603380<DL240
BL92-41-79.5ssF-trend22.316.20.735.42200070<DL<DL950630<DL150120180220
BL92-41-122.4pgnF-trend30.117.10.571.238000<DL<DL<DL<DL2540<DL<DL2280100170
BL92-41-165.9pgnF-trend27.716.80.600.9460000<DL<DL<DL7201600<DL<DL2320<DL240
BL98-58-136.7pgnF-trend33.017.00.527.496039804810<DL6709930460<DL21409805960
BL98-58-138.2pgnF-trend20.815.80.761.71600057802150<DL1840383060<DL1100250350
BL98-58-143.9pgnF-trend20.415.90.782.021002660<DL<DL3540870<DL<DL298023001050
BL98-58-155.0pgnF-trend22.115.80.711.8120001160<DL<DL<DL870<DL<DL2810310280
BL98-58-178.3pgnF-trend40.418.20.452.9240000<DL<DL<DL<DL1360<DL<DL3020120180
BL91-34-148.2ssF-trend25.320.30.800.6179060<DL<DL920560<DL150240<DL<DL
BL91-34-154.1pgnF-trend28.917.00.5912.5139041208101320700285011014010403902060
BL91-34-169.1pgnF-trend23.516.40.702.957301010430194014801700<DL58018507405050
BL06-61-97.5ssF-trend24.119.50.813.73030100400<DL1210370<DL<DL<DL<DL100
BL06-61-100.3ssF-trend20.016.60.830.6192070410<DL1830650<DL<DL<DL<DL50
BL06-61-108.8ssF-trend28.523.70.837.82510<DL740<DL650260<DL<DL<DL<DL130
BL06-61-117.0ssF-trend25.521.10.831.52120<DL260<DL860240<DL<DL<DL<DL<DL
BL06-61-121.7ssF-trend28.023.80.853.13500<DL140<DL530200<DL<DL<DL<DL<DL
BL06-61-127.6ssF-trend32.225.50.7928.41800090270<DL610370<DL<DL120<DL290
BL06-61-135.0ssF-trend27.223.30.862.63380<DL610<DL770510<DL<DL<DL<DL<DL
BL06-61-144.0ssF-trend22.819.90.871.64850<DL790<DL1340390<DL<DL<DL<DL<DL
BL06-61-147.5ssF-trend33.627.70.831.24220<DL780<DL980610<DL<DL<DL<DL<DL
BL06-61-156.0ssF-trend23.718.50.780.91610<DL270<DL850260<DL<DL<DL<DL<DL
BL06-61-165.0ssF-trend25.118.60.740.41920<DL330<DL520170<DL<DL<DL<DL<DL
BL06-61-169.5ssF-trend24.219.20.791.61820<DL370<DL620460<DL<DL160<DL<DL
BL06-61-176.5ssF-trend24.917.30.702.02230<DL1205054036090<DL410<DL80
BL06-61-186.2ssF-trend68.121.00.313.44300000490190210530310850125024802703190
BL06-61-187.6ssF-trend49.521.10.432.212000013015070570260801101280210230
BL06-61-190.7ssF-trend26.516.60.624.2100000270370<DL790620<DL130260<DL630
BL06-61-199.1pgnF-trend67.021.50.328.5n.a.n.a.25024043047011012031803301220
BL06-61-208.8pgnF-trend27.817.40.639.6n.a.n.a.50067064014701001802500400820
BL06-61-225.7pgnF-trend18.416.90.920.6n.a.n.a.220280460870<DL605110650200
BL06-61-237.6pgnF-trend24.215.80.6511.5n.a.n.a.320130064035907030519012101130
BL91-38-253.8pgnF-trend35.317.60.503.1n.a.n.a.19017057025501802003190350390
BL91-38-260.8pgnF-trend70.421.20.303.0n.a.n.a.ll012087027002403002330240450
BL06-60-104.5ssF-trend2l.l16.00.751.1n.a.n.a.26050350220<DL60704060
BL06-60-233.7ssF-trend24.218.00.7438.6n.a.n.a.430902802260<DL4014040310
BL06-60-235.2pgnF-trend51.7l9.l0.374.6n.a.n.a.6105702803220ll03904590740530
BL06-60-244.0pgnF-trend38.117.30.467.7n.a.n.a.1808208909901002005670950360
BL92-45-107.2ssF-trend20.216.40.811.1n.a.n.a.<DL<DL920460<DL<DL10<DL30
BL92-45-119.3ssF-trend19.516.50.852.2n.a.n.a.<DL<DL690740<DL<DL10<DL50
BL92-45-129.5ssF-trend20.216.00.794.9n.a.n.a.7030970620<DL<DL<DL<DL130
BL92-45-136.8ssF-trend22.117.30.780.9n.a.n.a.<DL<DL91085030<DL2010<DL
BL92-45-138.0pgnF-trend25.116.80.6718.2n.a.n.a.<DL100510122040<DL230130690
BL92-45-142.0pgnF-trend40.7l9.l0.4734.5n.a.n.a.<DL140780310050<DL16401601800
BL92-45-152.2pgnF-trend269.342.30.168.0n.a.n.a.271028201510307025041023704606020
BL92-43-86.9ssF-trend20.4l6.l0.791.2n.a.n.a.10030830960<DL140202030
BL92-43-96.3ssF-trend29.222.10.760.7n.a.n.a.10030179064040<DL201030
BL92-43-110.9ssF-trend18.615.00.810.7n.a.n.a.ll03012l01070807010080
BL92-43-122.4ssF-trend20.716.40.793.8n.a.n.a.14060800700404013040ll0
BL92-43-123.8ssF-trend19.815.50.780.7n.a.n.a.ll0<DL10801080<DL160<DL<DL<DL
BL92-43-133.0ssF-trend282.640.70.144.3n.a.n.a.12017010108701170153017402307920
BL92-43-147.0pgnF-trend26.816.20.619.2n.a.n.a.2305107901760ll0<DL2100190620
BL92-43-173.8pgnF-trend45.418.30.403.4n.a.n.a.25072063059601402605830270460
BL92-43-189.8pgnF-trend34.7l7.l0.492.3n.a.n.a.8502600108051001701702480100380
BL92-43-205.9pgnF-trend43.019.20.453.2n.a.n.a.360790109028001701903140130330
BL06-65-69.4ssF-trend29.823.40.791.6n.a.n.a.310405005804020302020
BL06-65-87.4ssF-trend*0.665.3n.a.n.a.12208086061040<DL101060
BL06-65-99.4ssF-trend19.315.50.812.3n.a.n.a.2504097056030<DL20<DL70
BL06-65-111.7ssF-trendl9.ll5.l0.7912.7n.a.n.a.150<DL5702630<DL30<DL<DL120
BL06-65-123.7ssF-trend23.318.70.8010.4n.a.n.a.1903058054030101010170
BL06-65-132.5ssF-trend69.820.40.293.9n.a.n.a.330704201800600144031205702960
BL06-65-142.9ssF-trend**0.6912.4n.a.n.a.4205024030060<DLll04040
BL06-65-144.3pgnF-trend28.615.70.550.8n.a.n.a.1508073079090<DL138012040
BL06-65-147.3pgnF-trend32.616.80.524.2n.a.n.a.17070260310210<DL195078090
BL06-65-162.8pgnF-trend39.617.50.4426.0n.a.n.a.9750430182077012060400050700
BL06-65-170.0pgnF-trend63.120.90.3334.2n.a.n.a.130ll06304502508014000330920
BL06-65-177.3pgnF-trend30.316.60.550.8n.a.n.a.12l08201970650330<DL96020100
BL06-65-198.6pgnF-trend31.617.30.550.4n.a.n.a.650390500900ll030770<DL<DL
BL06-65-222.4pgnF-trend36.216.80.460.6n.a.n.a.61304120185024408403906090760570
BL92-47-124.0ssF-trend25.520.00.7824.3n.a.n.a.190801990175060<DL3040370
BL92-48-110.2ssF-trend24.517.90.732.0n.a.n.a.904012l0540<DL<DL1205050
BL92-48-202.1ssF-trend22.217.20.780.8n.a.n.a.100408702530605402507060
BL92-50-244.1ssF-trend21.4l6.l0.7517.0n.a.n.a.9010062098040<DL330120680
BL92-50-250.0pgnF-trend31.017.00.554.3n.a.n.a.491069902900011904602204400024905160
BL92-50-270.8pgnF-trend31.717.50.556.0n.a.n.a.389063001000022801160170850012401420
BL92-50-280.1pgnF-trend30.616.80.551.4n.a.n.a.2080243013702260230<DL50406501130
BL07-67-43.7ssG-trendll3.225.40.226.4n.a.n.a.ll021062010305102210610010503260
BL07-67-57.6ssG-trend24.816.20.652.5n.a.n.a.3906507903030400140720320270
BL07-67-60.0ggnG-trend26.316.40.622.6n.a.n.a.50709509908080510650410
BL07-67-187.3ggnG-trend52.4l8.l0.3410.3n.a.n.a.300501060690250ll01500018504170
BL07-67-230.2qmsG-trend22.315.90.719.9n.a.n.a.2040690630130501850360530
BL06-64-52.4ssG-trend61.920.00.32366.3n.a.n.a.1330235082015000100056012l066024000
BL06-64-80.2ssG-trend29.220.90.7213.0n.a.n.a.21017010706250<DL<DL15050250
BL06-64-93.5ssG-trend32.820.60.633.0n.a.n.a.50ll0790330<DL305050100
BL06-64-98.0ssG-trend25.816.70.65ll.3n.a.n.a.4605206101140905038050420
BL06-64-111.3ggnG-trend21.415.90.742.0n.a.n.a.40<DL710490ll0402320590100
BL06-62-88.4ssG-trend22.516.20.725.0n.a.n.a.5040750390<DL10013060200
BL06-62-116.6ssG-trend20.815.90.7612.9n.a.n.a.3101808602960<DL280ll080640
BL06-62-155.8ssG-trend31.516.90.546.1n.a.n.a.8014069050011010027050310
BL06-62-220.9qmsG-trend25.116.30.653.4n.a.n.a.13018077054026030950770210
BL06-62-252.2qmsG-trend25.416.40.655.5n.a.n.a.4080580190120401680490250
BL06-63-250.3ssG-trend25.716.50.641.1n.a.n.a.20<DL810470<DL30301090
BL06-63-300.2ssG-trend22.116.10.730.3n.a.n.a.105093034012090702020
BL06-63-315.5ssG-trend23.016.20.711.1n.a.n.a.210150600530220401703050
BL06-63-318.1qmsG-trend21.916.20.746.5n.a.n.a.9020094031038020320220240
BL07-69-55.0ssG-trend18.915.40.828.6n.a.n.a.20<DL840310<DL70180100180
BL07-69-84.8ssG-trend17.815.10.853.1n.a.n.a.10<DL830190<DL30302050
BL07-69-126.1ssG-trend20.215.60.777.5n.a.n.a.10101020360<DL404040200
BL07-69-165.1ssG-trend18.815.50.826.3n.a.n.a.0<DL6802301040302090
BL07-69-205.0ssG-trend25.016.60.667.6n.a.n.a.1040135026060703030200
BL07-69-230.2ssG-trend35.317.30.495.5n.a.n.a.601007203901901301150200220
BL07-69-239.7ssG-trend19.515.50.790.3n.a.n.a.2040101042090100870390520
BL07-69-250.2ssG-trend55.119.50.354.8n.a.n.a.10309805801102071025060
BL07-69-256.2ssG-trend19.315.40.800.7n.a.n.a.80<DL6309003401305670270250
BL07-69-261.9ssG-trend35.418.20.529.2n.a.n.a.40<DL8104102101201230210220
BL07-69-266.0ggnG-trend26.416.30.625.9n.a.n.a.20401070440130110910420550
BL07-69-272.9ggnG-trend20.015.60.781.4n.a.n.a.10309505301003065024050
BL07-69-285.9ggnG-trend19.715.60.792.0n.a.n.a.6060730120038080885037080
BL07-69-311.5ggnG-trend37.517.80.483.2n.a.n.a.80606808903001305720280260
BL07-69-337.4ggnG-trend31.517.20.551.8n.a.n.a.1101106307608090315026090
BL07-69-343.1qmsG-trend128.627.40.215.8n.a.n.a.60130102057062031017704901500
BL07-69-356.3qmsG-trend31.116.80.543.5n.a.n.a.5060530210180301880700220
BL07-69-377.9qmsG-trend36.617.30.4718.9n.a.n.a.4090560450140301020510860
BL07-69-393.3qmsG-trend20.416.00.780.8n.a.n.a.305045026080301120280230
BL07-68-118.2ssG-trend21.616.00.741.2n.a.n.a.2030102016405028014060110
BL07-68-238.1ssG-trend21.215.90.754.8n.a.n.a.3070840500<DL150170120240
BL07-68-417.5ssG-trend173.631.80.184.5n.a.n.a.1040380290330137010103301610
BL07-68-431.4qmsG-trend24.316.40.670.7n.a.n.a.2020580140609044011030
BL07-70-40.4ssG-trend20.616.10.783.6n.a.n.a.80<DL910390<DL1307030220
BL07-70-71.1ssG-trend22.116.30.741.2n.a.n.a.70<DL80049040280470220240
BL07-70-101.1ssG-trend25.016.80.671.7n.a.n.a.702098035040130190140460
BL07-70-130.3ssG-trend30.018.40.616.2n.a.n.a.11014069052070<DL200170650
BL07-70-160.2ssG-trend49.719.30.393.7n.a.n.a.330280490800170146016009801450
BL07-70-190.1ssG-trend24.917.60.711.6n.a.n.a.6030550320<DL<DL404050
BL07-70-210.8ssG-trend70.921.10.303.8n.a.n.a.7409201810103017102840467015006460
BL07-70-215.1ssG-trend23.816.40.690.4n.a.n.a.201708302501603072020020
BL07-70-220.6ssG-trend22.117.50.791.8n.a.n.a.70<DL390320100<DL1806090
BL07-70-250.9ssG-trend21.216.60.781.7n.a.n.a.602094024010050<DL8080
BL07-70-280.0ssG-trend24.017.80.740.3n.a.n.a.6040620460<DL40807020
BL07-70-310.1ssG-trend109.126.30.244.0n.a.n.a.140430260320310136029507102060
BL07-70-339.9ssG-trend20.316.50.810.8n.a.n.a.903085069030<DL24014070
BL07-70-360.4ssG-trend26.717.10.643.3n.a.n.a.703010002406040110120190
BL07-70-370.4ssG-trend260.241.80.164.1n.a.n.a.24029083026088099021003404870
BL07-70-378.9ssG-trend29.218.20.622.3n.a.n.a.250606302406011060110120
BL07-70-386.5qmsG-trend43.018.30.431.4n.a.n.a.170170400370990602905001010
BL07-70-391.3qmsG-trend34.418.50.548.3n.a.n.a.9012066015903105018801020700
BL07-70-410.0qmsG-trend59.019.40.3313.3n.a.n.a.130120720340350150410016602360
BL07-70-433.3qmsG-trend21.616.20.751.5n.a.n.a.6302101150840330210250001890770
BL07-70-447.7qmsG-trend57.720.40.355.3n.a.n.a.1802206706304402001100015501110

Notes: Lith. = lithology (ss = Thelon Fmn. sandstone; pgn = paragneiss; ggn = granitic gneiss; qms = quartz+muscovite schist); n.a. = not analyzed; <DL = below analytical detection limit, which is 1 ppb or less for all elements; * = 204Pb below analytical detection limit

Contents

GeoRef

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