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Al 'Ays Complex

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Journal Article
Journal: Economic Geology
Published: 01 November 2008
Economic Geology (2008) 103 (7): 1507–1529.
...H. M. Prichard; C. R. Neary; P. C. Fisher; M. J. O’Hara Abstract The AlAys ophiolite complex in Saudi Arabia is an example of an ophiolite that contains anomalous concentrations of all six platinum group elements (PGE) in podiform chromitite with maximum values of 2,570 ppb Pt, 6,870 ppb Pd, 840...
FIGURES | View All (13)
Image
Map of the Al ‘Ays ophiolite complex showing the positions of the samples of chromitite analyzed for PGE and shown in Table 1. Numbers show sample locations. Those in bold have Cr2O3 values of greater than 65 wt percent and those in bold and italic have the two lowest Cr2O3 values. d indicates a disseminated chromite sample. The dashed lines show the trend of chromitites with the same Cr/Fe ratio of between 0 and 2. The map is adapted from Neary (1974).
Published: 01 November 2008
F ig . 1. Map of the AlAys ophiolite complex showing the positions of the samples of chromitite analyzed for PGE and shown in Table 1 . Numbers show sample locations. Those in bold have Cr 2 O 3 values of greater than 65 wt percent and those in bold and italic have the two lowest Cr 2 O 3
Journal Article
Published: 01 July 2003
Bulletin de la Société Géologique de France (2003) 174 (4): 373–381.
...Abdessalem El Ghali; Claude Bobier; Noureddine Ben Ayed Abstract The recent sedimentary basins in Central Tunisia correspond to a set of depocenters with complex geometry which are bounded by E-W, N070 and N-S brittle structures. These bordering faults, active during Eocene and Cretaceous times...
Image
Plot of Cr# versus Mg# for Al ‘Ays (black circles) showing the composition of chromitite from ophiolite complexes worldwide (outlined with a black line) (after Barnes and Roeder, 2001).
Published: 01 November 2008
F ig . 3. Plot of Cr# versus Mg# for AlAys (black circles) showing the composition of chromitite from ophiolite complexes worldwide (outlined with a black line) (after Barnes and Roeder, 2001 ).
Image
Photomicrographs illustrating the difference in shape between ophiolitic (a and b) and layered complex (c and d) chromite grains. (a) Al ‘Ays, Saudi Arabia; (b) Semail, Oman; (c) Bushveld, RSA; and (d) Stillwater, USA.
Published: 01 June 2018
Fig. 1. Photomicrographs illustrating the difference in shape between ophiolitic ( a and b ) and layered complex ( c and d ) chromite grains. ( a ) AlAys, Saudi Arabia; ( b ) Semail, Oman; ( c ) Bushveld, RSA; and ( d ) Stillwater, USA.
Journal Article
Published: 01 December 2014
Jour. Geol. Soc. India (2014) 84 (6): 709–726.
... method of presentation of the alteration data, the author on an experimental basis has used Alteration Box plot (Large et al. 2001) and the Alteration Index (AI) (Ishikawa, 1969) to depict the hydrothermal alteration in the environment other than the volcanic hosted massive sulphide depositional...
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Book Chapter

Author(s)
Biddle Kevin T
Series: AAPG Memoir
Published: 01 January 1991
EISBN: 9781629811147
... Abstract “The most distinctive characteristic of the Los Angeles basin“The most distinctive characteristic of the Los Angeles basin is its structural relief and complexity in relation to its age and size” (Yerkes et aI., 1965, p. AI6); however, its very complexity caused no small amount...
Series: AAPG Memoir
Published: 01 January 1991
DOI: 10.1306/M52531
EISBN: 9781629811147
Journal Article
Published: 01 September 2010
Geological Magazine (2011) 148 (2): 250–268.
... (Middlemost, 1994 ; Fig. 5 a), the investigated granitoids are classified as granite, granodiorite, quartz monzonite, monzonite and quartz diorite. The rocks dominantly plot in the sub-alkaline field of the diagram of Irvine & Baragar ( 1971 ) ( Fig. 5 a). The agpaitic index (AI=mol (Na+K/Al)) shows...
Journal Article
Published: 01 August 1969
American Mineralogist (1969) 54 (7-8): 1084–1100.
... pairs from the Stillwater Complex by a combination of wet and microprobe methods; both the parent chromite and ferritchromit can be expressed by the general formula (Mg, Fe 2+ ) (Cr, Al, Fe 3+ ) 2 O 4 , and neither contains cation deficiencies of the maghemite type. The alteration is essentially...
Journal Article
Journal: Economic Geology
Published: 01 August 2001
Economic Geology (2001) 96 (5): 1055–1072.
... medium-grained quartz-porphyritic pumice breccia, black mudstone, and crystal-rich volcaniclastic sandstone, overlying a thick homogeneous sequence of rhyolitic pumice breccia. The major alteration minerals at Rosebery are arranged in a complex series of zones passing away from the deposit—quartz...
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Journal Article
Published: 01 April 1996
Journal of the Geological Society (1996) 153 (2): 323–328.
...H. M. PRICHARD; R. A. LORD; C. R. NEARY Abstract During the last ten years significant concentrations of Pt and Pd (more than 1000 ppb Pt + Pd) have been reported from several ophiolite complexes including Shetland, Leka, Al 'Ays, Zambales, Ceruja and Thetford. Similar studies on others, including...
Image
Geochemical data for major rock types plotted in alteration diagrams. A, B) Plot of the chlorite-carbonate-pyrite index (CCPI) of Large et al. (2001) on the y axis and the alteration index (AI) of Ishikawa et al. (1976) on the x axis; see text for explanation. A) Mafic to felsic volcanic rocks, gabbro, and ultramafic intrusions. B) Pre- and postmineralization felsic intrusions of the Windfall Intrusive Complex. Note the dashed arrows on the diagrams indicate the dominant trends. C, D) Pearce element ratio (PER) diagrams for pre- and postmineralization intrusions of the Windfall Intrusive Complex using molar 2Ca + Na + K/Zr versus molar Al/Zr, where Zr is the conserved element. Note that data on the feldspar control line define the least altered samples, whereas data that trend downward toward the muscovite control line define sericite-altered samples. Abbreviations: f.g. = fine-grained, QFP = quartz-feldspar porphyry, Qz. = quartz.
Published: 01 August 2023
Fig. 7. Geochemical data for major rock types plotted in alteration diagrams. A, B) Plot of the chlorite-carbonate-pyrite index (CCPI) of Large et al. ( 2001 ) on the y axis and the alteration index (AI) of Ishikawa et al. ( 1976 ) on the x axis; see text for explanation. A) Mafic to felsic
Image
(a) Distribution of major basement terranes and adjacent sedimentary basins in Central Australia. (b) Generalized map of the eastern Arunta Region and major Alice Springs orogen-age structures in surrounding areas, dashed red box corresponds to Figure 2. (c) Schematic cross-section (A–A′) displaying the structural architecture of the Alice Springs orogen. Abbreviations: AI, Arunta Inlier; AB, Amadeus Basin; NB, Ngalia Basin; GB, Georgina Basin; PCI, Pine Creek Inlier; KB, Kimberley Basin; MB, McArthur Basin; PC, Pilbara Craton; YC, Yilgarn Craton; GC, Gawler Craton; OB, Officer Basin; SMC, Strangways Metamorphic Complex. Source: modified from Raimondo et al. 2011; Foster 2016; Silva et al. 2018; Varga et al. 2022.
Published: 04 April 2024
, Officer Basin; SMC, Strangways Metamorphic Complex. Source: modified from Raimondo et al. 2011 ; Foster 2016 ; Silva et al. 2018 ; Varga et al. 2022 .
Image
Palinspastic pre-Late Cretaceous restoration of the Rinkian mobile belt (western Greenland) to correlated magmatic and tectonometamorphic units on Baffin Island in northeast Canada (St-Onge et al., 2009). Correlated units are shown in the same color. Black dashed lines indicate boundaries of interpreted Paleoproterozoic sutures and gray dashed lines indicate magmatic arc fronts (St-Onge et al., 2009). The figure is modified from St-Onge et al. (2009). Abbreviations: AI = Ataa intrusive complex, CP = Cumberland Peninsula, DB = Disko Bugt, KF = Karrat Isfjord, RH = Red Head, SH = Svartenhuk Halvø, UF = Uummannaq Fjord, UP = Upernavik.
Published: 01 September 2013
boundaries of interpreted Paleoproterozoic sutures and gray dashed lines indicate magmatic arc fronts ( St-Onge et al., 2009 ). The figure is modified from St-Onge et al. (2009) . Abbreviations: AI = Ataa intrusive complex, CP = Cumberland Peninsula, DB = Disko Bugt, KF = Karrat Isfjord, RH = Red Head, SH
Series: GSA Special Papers
Published: 22 March 2023
DOI: 10.1130/2022.2558(11)
EISBN: 9780813795584
... nature of Earth systems adds complexity to AI ( Reichstein et al., 2019) . The physical, chemical, and biological processes and their interactions substantially influence the data patterns, resulting in numerous possibilities that are almost impossible to cover with a single training data set ( Maskey et...
FIGURES
Image
Laurentia-Baltica-Amazonia reconstruction for mid-Neoproterozoic time, showing major Archean, Paleoproterozoic, and Mesoproterozoic tectonic elements, and extent of the early Paleozoic Caledonian orogen of East Greenland, Scandinavia, and the British Isles, and its lateral extension into the Appalachian Mountains (modified from Cawood et al., 2007). Red arrow indicates clockwise rotation of Baltica that occurred between ca. 1270 Ma and ca. 1000 Ma (see text for discussion). AI—Amazonian inliers; RB—Rockall Bank; UA—Uppermost Allochthon; WTBC—West Troms Basement Complex.
Published: 21 July 2020
into the Appalachian Mountains (modified from Cawood et al., 2007 ). Red arrow indicates clockwise rotation of Baltica that occurred between ca. 1270 Ma and ca. 1000 Ma (see text for discussion). AI—Amazonian inliers; RB—Rockall Bank; UA—Uppermost Allochthon; WTBC—West Troms Basement Complex.
Image
Sketch map of the Antarctic Peninsula, showing main tectonic features (after Leat et al. 1995; Riley & Leat 1999). The Pacific margin magnetic anomaly approximately overlies the position of a Cretaceous magmatic arc batholith. The dykes sampled in this paper crop out in the Oscar II Coast and Black Coast areas (arrows in the diagram show dominant dyke trends). The Lully Foothills Seamount in the fore-arc complex forming Alexander Island (AI) is a sliver of a Jurassic ocean island or seamount which collided with the Antarctic Peninsula arc.
Published: 01 January 2002
II Coast and Black Coast areas (arrows in the diagram show dominant dyke trends). The Lully Foothills Seamount in the fore-arc complex forming Alexander Island (AI) is a sliver of a Jurassic ocean island or seamount which collided with the Antarctic Peninsula arc.
Image
A schematic illustration showing the typical stratigraphy and distribution of Pt and Pd in the different types of ophiolite complex: group 1 Pt, Pd, and chromitite poor, formed from too little melting, as in MORB-type ophiolites such as the Lizard ophiolite in Cornwall, UK; group 2 Pt-, Pd- and chromitite-rich formed at critical melting as the last sulfides melt and Pt and Pd are extracted from the mantle as in the Al ‘Ays, Shetland, and Leka ophiolites; group 3 Pt and Pd poor and chromitite rich, formed by melting beyond the critical value, with minor Pt and Pd concentrations with base metal sulfides in the gabbros as in Oman and Cyprus.
Published: 01 November 2008
-, Pd- and chromitite-rich formed at critical melting as the last sulfides melt and Pt and Pd are extracted from the mantle as in the AlAys, Shetland, and Leka ophiolites; group 3 Pt and Pd poor and chromitite rich, formed by melting beyond the critical value, with minor Pt and Pd concentrations
Image
(a) Location of Ocean Drilling Program (ODP) site 976 in the West Alborán Sea basin, with a schematic geological map of the surrounding Betic and Rif mountain chains (after Soto & Platt 1999). The metamorphic basement high (shaded) near site 976 (from Comas et al. 1992) is similar to the exposed metamorphic complexes of the Alborán Domain. Bathymetry contour interval is 200 m. AI: Alborán Island. (b) Schematic sequences of the metamorphic basement cored in ODP Hole 976B and Hole 976E (after Shipboard Scientific Party, 1996) show the location of the reaction zones. Recovered intervals are shown in black in the recovery column.
Published: 01 February 2002
) is similar to the exposed metamorphic complexes of the Alborán Domain. Bathymetry contour interval is 200 m. AI: Alborán Island. (b) Schematic sequences of the metamorphic basement cored in ODP Hole 976B and Hole 976E (after Shipboard Scientific Party, 1996 ) show the location of the reaction zones