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Abanico Formation

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Common lithologies observed within the Abanico Formation. (A) 40+ mafic-to-intermediate lava flows with subordinate tuff and volcaniclastic intervals (Guanaco member). Individual lava flows observed in the photograph are 2–20 m thick. (B) Andesitic block-and-ash flow deposit. Hammer for scale. (C) Welded and devitrified ignimbrite with fiamme. Pencil circled for scale. (D) Purple-weathering lahar deposit bearing small fossil mammal skull. Fingertip for scale. (E) Tilted strata composed of interbedded lahar and debris-flow deposits. Geologist (1.6 m) circled for scale. (F) Coarse, volcaniclastic debris-flow deposit with muddy sand matrix. Hammer for scale. (G) Cross-bedded and channelized sandstone and conglomerate deposits interbedded with fine-grained siltstone and mudstone. Arrows point to basal scour surfaces. (H) Laminated mudstone and siltstone interbedded with massive, muddy sandstone. Hammer for scale. (I) Cross-bedded pebble gravel and coarse sandstone. Pencil for scale. Map unit abbreviation (Qv) is as in Figure 4.
Published: 12 July 2018
Figure 6. Common lithologies observed within the Abanico Formation. (A) 40+ mafic-to-intermediate lava flows with subordinate tuff and volcaniclastic intervals (Guanaco member). Individual lava flows observed in the photograph are 2–20 m thick. (B) Andesitic block-and-ash flow deposit. Hammer
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Schematic stratigraphic sections of the Abanico Formation west and east of the El Baule fault zone. Sections were derived from map relationships and do not represent detailed measured sections. 40Ar/39Ar ages are recalculated relative to the Fish Canyon Tuff (FCT) sanidine. Map unit abbreviations as in Figure 4.
Published: 12 July 2018
Figure 7. Schematic stratigraphic sections of the Abanico Formation west and east of the El Baule fault zone. Sections were derived from map relationships and do not represent detailed measured sections. 40 Ar/ 39 Ar ages are recalculated relative to the Fish Canyon Tuff (FCT) sanidine. Map unit
Journal Article
Journal: GSA Bulletin
Published: 12 July 2018
GSA Bulletin (2019) 131 (1-2): 252–273.
...Figure 6. Common lithologies observed within the Abanico Formation. (A) 40+ mafic-to-intermediate lava flows with subordinate tuff and volcaniclastic intervals (Guanaco member). Individual lava flows observed in the photograph are 2–20 m thick. (B) Andesitic block-and-ash flow deposit. Hammer...
FIGURES
First thumbnail for: Late Cretaceous to Miocene volcanism, sedimentatio...
Second thumbnail for: Late Cretaceous to Miocene volcanism, sedimentatio...
Third thumbnail for: Late Cretaceous to Miocene volcanism, sedimentatio...
Journal Article
Journal: GSA Bulletin
Published: 01 December 2003
GSA Bulletin (2003) 115 (12): 1523–1537.
...Jan Olov Nyström; Mario Vergara; Diego Morata; Beatriz Levi Abstract This lithologic and geochemical study treats two Tertiary volcanic formations in the Andean foothills of central Chile deposited during and after an inferred culmination of crustal attenuation. The Abanico and Farellones...
FIGURES
First thumbnail for: Tertiary volcanism during extension in the Andean ...
Second thumbnail for: Tertiary volcanism during extension in the Andean ...
Third thumbnail for: Tertiary volcanism during extension in the Andean ...
Journal Article
Journal: Economic Geology
Published: 01 August 2005
Economic Geology (2005) 100 (5): 887–904.
.../Sm n ratios of 1.8 to 2.5 and Sm/Yb n of 1.8 to 2.8. The upper Oligocene to lower Miocene Abanico Formation (variously defined as the Los Pelambres, Abanico, or Coya Machalí Formations) ranges from basalt to rhyolite in composition and exhibits a broad southward transition from calc-alkaline...
FIGURES
First thumbnail for: Regional Geochemistry of Tertiary Igneous Rocks in...
Second thumbnail for: Regional Geochemistry of Tertiary Igneous Rocks in...
Third thumbnail for: Regional Geochemistry of Tertiary Igneous Rocks in...
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Overview of the map units. (A) View southwest across the Río Tinguiririca valley showing the Abanico Formation’s lower stratigraphic members Kll, Kga, Kgz, KTc, Ttl, and Ttu, and upper stratigraphic member Tg. Río Tinguiririca and reservoir labeled for scale. (B) Upper stratigraphic levels of the Abanico Formation (Tg, Trt, and Tr) are seen resting unconformably on the older Mesozoic stratigraphy (brownish red clastic unit [BRCU], Jbf, and Jrd) in slight angular unconformity. Cerro Alto del Padre is the prominent peak in right side of photo. The locations of radioisotopic ages are shown by boxes, and apparent bedding is shown by ball-and-sticks. Note the progressive decrease in apparent dip of bedding up section and the southeastern thinning and truncation of the Abanico Formation’s younger members. Map unit abbreviations are as in Figure 4. The town of Termas del Flaco is labeled for scale.
Published: 12 July 2018
Figure 5. Overview of the map units. (A) View southwest across the Río Tinguiririca valley showing the Abanico Formation’s lower stratigraphic members Kll, Kga, Kgz, KTc, Ttl, and Ttu, and upper stratigraphic member Tg. Río Tinguiririca and reservoir labeled for scale. (B) Upper stratigraphic
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Deformation style at the inverted eastern margin of the Abanico Basin. A. E-vergent anticline-syncline pair affecting Abanico Formation lava flows. View north from 399397mE, 6349379mN. B. Immediately to the east of (A), the Tertiary volcanic rocks are in fault contact with Mesozoic limestones of the Lo Valdes Formation along the El Fierro fault. View north from 400682mE, 6348304mN.
Published: 01 December 2015
Fig. 7 Deformation style at the inverted eastern margin of the Abanico Basin. A. E-vergent anticline-syncline pair affecting Abanico Formation lava flows. View north from 399397mE, 6349379mN. B. Immediately to the east of (A), the Tertiary volcanic rocks are in fault contact with Mesozoic
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(A) Plot of all geochronology data obtained in this study, sorted by age. 40Ar/39Ar ages are shown in black, and U-Pb zircon ages are in gray. The dashed line represents the oldest reliable age reported for the Abanico Formation prior to this study (ca. 36.2 Ma). Ages above and below the line generally pertain to the upper and lower Abanico Formation, respectively. Inset plot is a histogram of the combined age data. 40Ar/39Ar ages were recalculated relative to the Fish Canyon Tuff (FCT) sanidine (Table 1); only one age is shown for samples with multiple splits. (B) Stratigraphic position vs. age for volcanic intervals west of the El Baule fault zone. (C) Stratigraphic position vs. age for volcanic intervals east of the El Baule fault zone. Note that the slope of the linear regressions represents accumulation rate (m/m.y.).
Published: 12 July 2018
Figure 8. (A) Plot of all geochronology data obtained in this study, sorted by age. 40 Ar/ 39 Ar ages are shown in black, and U-Pb zircon ages are in gray. The dashed line represents the oldest reliable age reported for the Abanico Formation prior to this study (ca. 36.2 Ma). Ages above
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Three schematic end-member models depicting the evolution of an intra-arc basin and the proto–El Baule fault zone prior to Eocene–Miocene transpressive shortening in the Río Tinguiririca area. See Figure 4 unit abbreviations. BRCU—brownish red clastic unit. (A) Deposition of arc strata west of an active, west-dipping extensional fault system (proto–El Baule fault zone), or a relict fault-bounded range front (buttress unconformity). (B) Deposition of the lower Abanico Formation, followed by normal faulting, erosion of footwall strata, and accumulation of volcanic and volcaniclastic debris west of the fault zone. (C) Deposition of strata in a foreland basin west of an active, east-dipping contractional fault system. (D) Deposition of the lower Abanico Formation followed by contractional faulting, erosion of hanging-wall strata, and deposition of volcanogenic deposits in a foreland basin to the west. (E) Deposition of arc strata on a volcano-bounded arc platform without active faulting, forming a buttress unconformity with the older Mesozoic stratigraphy.
Published: 12 July 2018
strata west of an active, west-dipping extensional fault system (proto–El Baule fault zone), or a relict fault-bounded range front (buttress unconformity). (B) Deposition of the lower Abanico Formation, followed by normal faulting, erosion of footwall strata, and accumulation of volcanic
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Figure 13. Fertile MORB mantle (FMM) normalized diagrams for mantle-derived elements in basic lavas from the Abanico Formation and the upper member of the Farellones Formation. Normalization factors from Pearce and Parkinson (1993). SiO2 contents (wt%) of the samples in parentheses.
Published: 01 December 2003
Figure 13. Fertile MORB mantle (FMM) normalized diagrams for mantle-derived elements in basic lavas from the Abanico Formation and the upper member of the Farellones Formation. Normalization factors from Pearce and Parkinson (1993) . SiO 2 contents (wt%) of the samples in parentheses.
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 Figure 2. Geologic sketch map of the study area that includes the type localities of the Abanico (Oligocene; dark pattern) and Farellones (lower Miocene; light pattern) Formations east of Santiago, central Chile (white—alluvium, crosses—Tertiary granitoids). Modified from Thiele (1980), Beccar (1983), Villarroel (1990), Thiele et al. (1991), and Vergara et al. (1993). Santiago is situated at an altitude of ∼600 m, and Farellones village at 2450 m above sea level. The numbers show the localities of the 26 samples analyzed chemically for this study. Only one unaltered sample from the Cerro Abanico area, a paleo–geothermal field, was analyzed; otherwise, the volcanic rocks here are the same as in their northern continuation in the Mapocho Valley. The structural relationship at the contact between the Farellones and Abanico Formations is illustrated schematically in cross section for three localities (A–C; the wavy line in A represents an unconformity).
Published: 01 December 2003
Figure 2. Geologic sketch map of the study area that includes the type localities of the Abanico (Oligocene; dark pattern) and Farellones (lower Miocene; light pattern) Formations east of Santiago, central Chile (white—alluvium, crosses—Tertiary granitoids). Modified from Thiele (1980) , Beccar
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General stratigraphic framework of the central Principal Cordillera between ∼33°S and 36°S latitude, after Charrier et al. (1996). Results reported herein significantly revise the age of volcanic deposits previously mapped as the Abanico Formation in the Río Tinguiririca area. Fm.—Formation; QP—Quaternary–Pliocene; E—Early; M—Middle; L—Late; BRCU— brownish red clastic unit.
Published: 12 July 2018
Figure 3. General stratigraphic framework of the central Principal Cordillera between ∼33°S and 36°S latitude, after Charrier et al. (1996) . Results reported herein significantly revise the age of volcanic deposits previously mapped as the Abanico Formation in the Río Tinguiririca area. Fm
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Figure 3. Generalized lithostratigraphic column for the Abanico and Farellones Formations in their type localities east of Santiago, central Chile (location of type localities shown in Fig. 2; subordinate rock types within parentheses), with approximate positions of the analyzed samples of this study and published radiometric data. All samples are from lava flows except those marked with d—dike and p—pyroclastic material (from ash flows). The capital letters in parentheses specify composition: B—basalt; BA—basaltic andesite; A—andesite; D—dacite; and R—rhyolite. Wavy horizontal line—unconformity; unbroken line—conformable contact; and dashed line—fault. Lithology and subdivision into members are based on Beccar et al. (1986), Vergara et al. (1988), Villarroel (1990), Thiele et al. (1991), Vergara et al. (1993), and this study. The minimum thickness of the Abanico Formation is ∼3100 m (its base is covered by alluvium), and the thickness of the Farellones Formation is at least 2100 m (its top is an erosional surface).
Published: 01 December 2003
Figure 3. Generalized lithostratigraphic column for the Abanico and Farellones Formations in their type localities east of Santiago, central Chile (location of type localities shown in Fig. 2 ; subordinate rock types within parentheses), with approximate positions of the analyzed samples
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View of the NE-striking Saladillo fault system. About 800 m of Abanico Formation pyroclastic rocks were accumulated in a tectonic basin to the northwest of the fault system. The same structures were later reactivated as dextral-reverse faults and controlled the emplacement of andesitic and dacitic dikes and the Potrero Alto veins. Blue lines represent faults and black lines show stratigraphic contacts. View southwest from 380995mE, 6357149mN.
Published: 01 December 2015
Fig. 10 View of the NE-striking Saladillo fault system. About 800 m of Abanico Formation pyroclastic rocks were accumulated in a tectonic basin to the northwest of the fault system. The same structures were later reactivated as dextral-reverse faults and controlled the emplacement of andesitic
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Examples of syntectonic intrusions emplaced during E-W compression. In both cases the host rocks are basaltic-andesitic lava flows of the Abanico Formation. A. Gabbro-diorite dike emplaced in a dilational jog within a sinistral, NW- striking fault, at 383791mE, 6349678mN. The outcrop is horizontal. B. Rhyodacitic sills emplaced on slightly rotated dilational lenses, developed in the core of an E-vergent anticline. View south-southwest from 392885mE, 6363419mN.
Published: 01 December 2015
Fig. 12 Examples of syntectonic intrusions emplaced during E-W compression. In both cases the host rocks are basaltic-andesitic lava flows of the Abanico Formation. A. Gabbro-diorite dike emplaced in a dilational jog within a sinistral, NW- striking fault, at 383791mE, 6349678mN. The outcrop
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Generalized geologic map spanning Chile and western Argentina between 34°S and 36°S latitude. White box shows the location of the area mapped in this study (Fig. 4). Focal mechanisms are shown for upper-crustal (<100 km) earthquakes in the Principal Cordillera and Malargüe fold-and-thrust belt (FTB). Geologic map is modified after the Mapa Geológico de Chile (SERNAGEOMIN, 2003) and the Mapa Geológico de la República Argentina (SEGEMAR, 1997), with the age of the Abanico Formation deriving from results presented herein. Fm.—Formation.
Published: 12 July 2018
-and-thrust belt (FTB). Geologic map is modified after the Mapa Geológico de Chile ( SERNAGEOMIN, 2003 ) and the Mapa Geológico de la República Argentina ( SEGEMAR, 1997 ), with the age of the Abanico Formation deriving from results presented herein. Fm.—Formation.
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Figure 1. Location of the study area in central Chile. (A) Main physiographic features. The Central Valley is a graben that separates the Coast Range and the Andean Range south of Santiago. The stars represent Quaternary volcanic complexes (shown in more detail in C) belonging to the SVZ (from 33°S to 46°S, referred to as the northern part of the SVZ [NSVZ] between 33°S and 34°30′S and the central part of the SVZ [CSVZ] between 37°S and 41°30′S, separated by a transitional zone). (B) Schematic west-east profile from the Pacific Ocean to westernmost Argentina at the latitude of Santiago (vertical exaggeration = 2.5; modified from Levi et al., 1988). Pz—Paleozoic basement. The  Mesozoic–Cenozoic sequences, which predominantly consist of volcanic and volcaniclastic rocks, are indicated by the following abbreviations: J—Jurassic, LK—Lower to middle Cretaceous, UK—Upper Cretaceous, Tcv—Oligocene–lower Miocene rocks in the Central Valley graben, Tab—the Oligocene Abanico Formation, Tfa—the lower Miocene Farellones Formation, Tabe—Oligocene rocks usually referred to as the Abanico East Formation (not treated in this paper), and Q—Quaternary volcanic complexes. Regional unconformities and major faults are indicated with thick lines (normal faults delimit the Central Valley graben, and reverse faults [designated r] occur in the High Andes of Argentina and contiguous parts of Chile). (C) Distribution of the Abanico and Farellones Formations in the western foothills of the Andean Range (modified from SERNAGEOMIN, 2002; Vergara et al., 1988; Rivano et al., 1990). Río Blanco–Los Bronces and El Teniente are giant porphyry copper deposits.
Published: 01 December 2003
Miocene rocks in the Central Valley graben, Tab—the Oligocene Abanico Formation, Tfa—the lower Miocene Farellones Formation, Tabe—Oligocene rocks usually referred to as the Abanico East Formation (not treated in this paper), and Q—Quaternary volcanic complexes. Regional unconformities and major faults
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Simplified geologic map of central Chile, showing approximate locations of the 88 representative samples analyzed in this study and major Cu porphyry deposits. Right-hand column illustrates the approximate extent of the traditional terminology applied to the Oligocene volcanic rocks of central Chile, referred to as the Abanico Formation herein (see text for discussion). Age data in right-hand column from Vergara et al. (1988). Map modified after Rivano et al. (1993), Rivano and Sepulveda (1986), and Thiele (1979).
Published: 01 August 2005
of central Chile, referred to as the Abanico Formation herein (see text for discussion). Age data in right-hand column from Vergara et al. (1988) . Map modified after Rivano et al. (1993) , Rivano and Sepulveda (1986) , and Thiele (1979) .
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Same-scale regional plan view maps of (A) the New Guinea fold belt in Irian Jaya and (B) the Chilean segment of the Mesozoic-Tertiary central Chilean magmatic arc. The Fierro thrust location is simplified from Godoy et al. (1999). Note the remnant plates of the competent New Guinea Limestone and Farellones Formation in the center of the New Guinea and central Chilean fold and thrust belts, respectively. The units immediately underlying the competent plates comprise Mesozoic clastic packages in New Guinea and the Coya-Machalí and Abanico Formation volcaniclastic packages in central Chile. These underlying units are typically more highly deformed and folded and are exposed on both sides of the competent plate.
Published: 01 August 2005
Limestone and Farellones Formation in the center of the New Guinea and central Chilean fold and thrust belts, respectively. The units immediately underlying the competent plates comprise Mesozoic clastic packages in New Guinea and the Coya-Machalí and Abanico Formation volcaniclastic packages in central
Journal Article
Journal: Economic Geology
Published: 01 December 2015
Economic Geology (2015) 110 (8): 1995–2023.
...Fig. 7 Deformation style at the inverted eastern margin of the Abanico Basin. A. E-vergent anticline-syncline pair affecting Abanico Formation lava flows. View north from 399397mE, 6349379mN. B. Immediately to the east of (A), the Tertiary volcanic rocks are in fault contact with Mesozoic...
FIGURES
First thumbnail for: Structural Evolution of the Rio Blanco-Los Bronces...
Second thumbnail for: Structural Evolution of the Rio Blanco-Los Bronces...
Third thumbnail for: Structural Evolution of the Rio Blanco-Los Bronces...