Multiple sources for the Coastal Batholith of central Chile (31–34°S): geochemical and Sr–Nd isotopic evidence and tectonic implications

Parada, Miguel A.; Nyström, Jan Olov; Levi, Beatriz

doi:10.1016/s0024-4937(98)00080-2

Cited by 121 publications

(72 citation statements)

References 28 publications

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“…The southern intrusives (Cerro Mesón Alto and La Gloria pluton) are slightly more radiogenic in their 87 Sr/ 86 Sr i ratio than the northern group (San Francisco Batholith and Yerba Loca stock) at equivalent 143 Nd/ 144 Nd i values. As a result of this characteristic the southern group plots inside many fields: the Chilean Coastal Batholith of central Chile (31°-34°S) (Parada et al, 1999), where its depleted portion overlaps with the SSVZ volcanic field (Kilian and Behrmann, 2003), Teniente Volcanic Complex (Kay et al, 2005) and in parts with the Farellones and Abanico formations (Nyström et al, 2003). Río Blanco-Los Bronces porphyry (Stern and Skewes, 1995) 87 Sr/ 86 Sr i ratios are similar with the SSVZ volcanic field but 143 Nd/ 144 Nd i values are less depleted compared to the rest of the rock groups of the depleted quadrant.…”

Section: Isotopic Characteristicsmentioning

confidence: 99%

“…In the initial 143 Nd/ 144 Nd versus Th/La diagram, the data (Fig. 10c) (Lucassen et al, 2004), central Chilean Coastal Batholith rocks (Parada et al, 1999), Pacific pelagic sediments (Othmann et al, 1989), Teniente Volcanic Complex (Kay et al, 2005), Río Blanco-Los Bronces porphyries (Stern and Skewes, 1995), Farellones and Abanico formations (Nyström et al, 2003), southernmost Southern Volcanic Zone (SSVZ) (Kilian and Behrmann, 2003) and DM (Michard et al, 1985;McCulloch and Black, 1984).…”

Section: Isotopic Characteristicsmentioning

confidence: 99%

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Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematics

Deckart

Godoy²,

Bertens

et al. 2010

AndGeo

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ABSTRACT. Four Middle-to-Late Miocene barren plutonic complexes that occur between the giant porphyry copper deposits of the central Chilean Andes were selected for U-Pb LA-ICPMS geochronology and Hf-isotope systematics on single zircon grains. Major and trace elements and Sr-Nd-Hf isotope whole rock geochemical studies were undertaken to compare with slightly younger or coeval barren and fertile intrusive rocks between 32° and 34°S. The studied granitoids yield resolvable crystallization ages of 11.3±0.1 Ma (Cerro Mesón Alto massif), 10.3±0.2 Ma (La Gloria pluton), 14.9±0.2 Ma/14.9±0.1 Ma (Yerba Loca stock) and 11.2±0.1 Ma/14.7±0.1 Ma (San Francisco Batholith). Major and trace elements discard an adakitic signature as suggested for coeval porphyric intrusions at 32°S, slightly younger mineralized porphyries at Río Blanco-Los Bronces deposit and other Cenozoic adakites. Volcanic host rocks are less fractionated than the intrusive rock units. The same observation can be made for the unmineralized northern plutons compared to the southern ones. Initial Sr-Nd isotope data show insignificant variation (0.703761-0.704118 and 0.512758-0.512882), plotting in the mantle array. Trace element enrichment can be explained by addition of subducted-slab fluids and/or terrigenous sediments to the mantle wedge prior to and/or slight crustal input during magma ascent. Zircon grains separated from these barren intrusives share a similar initial εHf-data variation for the younger age group (10-12 Ma; 7.04-9.54) and show a more scattered range for the older one (14-15 Ma; 8.50-15.34); both sets plot between the DM and CHUR evolution lines. There is evidence that magma evolution was slightly distinct through time from older to younger barren magmatism, compared to a few fertile porphyritic rocks from Río Blanco-Los Bronces porphyry copper deposit. It is suggested that chronological inconsistencies within these complexes might be related to differential shortening across the NE-SW-trending Yeso Valley transfer fault, assumed as coeval, which also explains the local lack of easterly magmatic arc front migration. Francisco). Elementos mayores y trazas excluyen una característica adakítica, como ha sido sugerido para los intrusivos porfídicos a los 32°S, los pórfidos mineralizados ligeramente más jóvenes de Río Blanco-Los Bronces y otras adakitas del Cenozoico. Las rocas volcánicas de caja son menos fraccionadas que las unidades de rocas intrusivas. La misma conclusión se obtiene con relación a los plutones de la zona norte comparados a los del sur. Valores isotópico iniciales Sr-Nd muestran una variación insignificante (0,703761-0,704118 y 0,512758-0,512882) en el campo del manto. El enriquecimiento de elementos traza puede ser explicado a través de una adición de fluidos de la placa subducida y/o por sedimentos terrígenos transportados hacia la cuña de manto y/o por un leve aporte cortical durante el ascenso del magma. Granos de circón separados de los intrusivos estériles del grupo más joven (10-12 Ma; 7,04-9,54) comparten valores i...

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Section: Isotopic Characteristicsmentioning

confidence: 99%

Section: Isotopic Characteristicsmentioning

confidence: 99%

Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematics

Deckart

Godoy²,

Bertens

et al. 2010

AndGeo

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“…Figure 1: a) Distribution of late Triassic-early Jurassic magmatism in the Cordillera de la Costa between 29° and 37°S; compiled after Godoy (1970), Hervé and Munizaga (1978), Dávila et al (1979), Gajardo (1981), Gana and Hervé (1983), Mpodozis and Kay (1992), Parada et al (1999) and Willner et al (2004). LF: Lanalhue Fault , BBFZ: Bío-Bío Fault Zone (Rehak et al 2008); IL: Itata Lineament; Maule Lineament; PVF: Pichilemu-Vichuquén Fault (Willner et al 2005); MA: Melipilla Anomaly (Yañez et al 1998).…”

Section: Figuresmentioning

confidence: 99%

“…The gray area represents the compositions of the Paleozoic metamorphic basement at the Cordillera de la Costa south of the 37°S (adapted from Lucassen et al 2004). Parada et al 1999, Lucassen et al 2004, for the subarc subcontinental mantle of northern Chile (18°-27°S; Lucassen et al 2006), and for average of the Pacific MORB (Petrological database of the ocean floor http://petdb.org); the Nd isotope composition is corrected for in-situ decay to 210 Ma using a 147 Sm/ 144 Nd ratio of 0.214). The Sr isotope composition of Bulk Silicate Earth (BSE) is calculated at 210 Ma assuming a Rb/Sr ratio of 0.03 (McDonough and Sun, 1995) and a present day 87 Sr/ 86 Sr of 0.7045 (Salters and Stracke, 2004).…”

Section: Figuresmentioning

confidence: 99%

Origin of fayalite granitoids: New insights from the Cobquecura Pluton, Chile, and its metapelitic xenoliths

Vásquez¹,

Glodny²,

Franz³

et al. 2009

Lithos

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Fayalite granitoids of the Cobquecura Pluton, Central Chile, occur in an active continental margin setting, which is unusual for such rocks. They are closely associated with gabbros, and both lithologies contain hercynite-rich, Fe-rich metapelitic xenoliths. The primitive magmas of the Cobquecura Pluton are derived from a mafic source, similar to the regional subarc subcontinental mantle. Sr-Nd-Pb isotope data demonstrate that crustal contributions were important in the petrogenesis of the fayalite granitoids. The crustal contribution, however, does not consist of rocks similar to the regionally exposed Paleozoic basement rocks, but rather resembles partial melts derived from metapelitic rocks at depth. The corresponding restites are the hercynite-rich xenoliths. A relatively high content of rare earth elements and high field strength elements in the fayalite granitoids is linked to selective assimilation of crust. This is evident from the abundant xenoliths that are entrained in the fayalite granitoids, and whose leucosomes are rich in accessory minerals carrying these elements. Such Fe-rich rocks similar to the hercynite-rich xenoliths could have acted as a chemical buffer keeping the oxygen fugacity low, which is crucial for the generation of fayalite bearing granitoids.

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“…This complex is also composed of bimodal association with leucogranites, gabbros and mingling structures (Gana, 1991, Parada et al, 1999. Whole rock Rb/Sr ages range between 200 and 220 Ma (Irwin et al, 1988).…”

Section: Ianigla Mendoza Argentinamentioning

confidence: 99%

International Lateinamerika-Kolloquium 2009

Möller-McNett¹

2009

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Multiple sources for the Coastal Batholith of central Chile (31–34°S): geochemical and Sr–Nd isotopic evidence and tectonic implications

Cited by 121 publications

References 28 publications

Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematics

Barren Miocene granitoids in the Central Andean metallogenic belt, Chile: Geochemistry and Nd-Hf and U-Pb isotope systematics

Origin of fayalite granitoids: New insights from the Cobquecura Pluton, Chile, and its metapelitic xenoliths

International Lateinamerika-Kolloquium 2009

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