Aporte cortical en la genesis del volcanismo bimodal Triasico de la Cordillera de la Costa, Chile central.
Crustal contribution in the genesis of the bimodal Triassic volcanism from the Coastal Range, central Chile
| dc.contributor | en-US | |
| dc.creator | Morata, Diego | |
| dc.creator | Aguirre, Luis | |
| dc.creator | Oyarzun, Marcela | |
| dc.creator | Vergara, Mario | |
| dc.date | 2010-06-30 | |
| dc.identifier | http://www.andeangeology.cl/index.php/revista1/article/view/V27n1-a06 | |
| dc.identifier | 10.5027/andgeoV27n1-a06 | |
| dc.description | RESUMEN:El volcanismo Triasico en la Cordillera de la Costa de Chile central esta representado por la Formacion Pichidangui (31°54'-32°15'S), constituida por flujos de lavas acidas y basicas con intercalaciones de cuerpos subvolcanicos y rocas sedimentarias. Ambos tipos de lavas presentan un metamorfismo no deformativo de muy bajo a bajo grado. Las caracteristicas geoquimicas de estas lavas corresponden a las de la serie toleitica, con valores de Nb/Y entre 0,20 y 0,17. Los bajos valores de [mg] en las rocas basicas son indicativos de liquidos no primarios. Las diferencias observadas en elementos traza inmoviles y tierras raras (LREE/HREE, Eu/Eu*) entre las rocas acidas y basicas son consistentes con sus signaturas isotopicas, cuyos valores iniciales son: (87Sr/86Sr)o 0,70397-0,70597 y (143Nd/144Nd)o 0,512515-0,512608 para las rocas basicas y 0,70514-0,71161 a 0,512108-0,512526 en las acidas. Estas diferencias geoquimicas e isotopicas entre ambos tipos de lavas se interpretan como consecuencia de diferentes tasas de contaminacion cortical a partir de una fuente mantelica enriquecida, con un componente litosferico, en un ambiente extensional intracontinental, seguido por cristalizacion fraccionada para generar los liquidos acidos y basicos. Las similitudes geoquimicas e isotopicas observadas entre las rocas basicas del Triasico y los gabros del Jurasico Inferior del Complejo Limari de la Cordillera de la Costa de Chile central se interpretan como la consecuencia de una genesis comun para ambos magmatismos, que estaria relacionada con la evolucion mesozoica del margen pacifico de Gondwana. | es-ES |
| dc.description | Triassic volcanism in the Coastal Range of central Chile is represented by the Pichidangui Formation (31°54' to 32°15'S) composed of acid and basic lava flows and sub-volcanic intrusives with some sedimentary intercalations. Both rock types have been affected by non-deformational very low- to low-grade metamorphism. Their geochemical characteristics indicate a tholeiitic affinity, with Nb/Y ratios ranging from 0.20-0.17. Low [mg] values in the basic rocks are indicative of non-primitive liquids. Differences in immobile trace element and REE (LREE/HREE, Eu/Eu*) between basic and acid rocks are consistent with their isotopic signature, with initial ratios of (87Sr/86Sr)o and (143Nd/144Nd)o ranging from 0.70397 to 0.70597 and from 0.512515 to 0.512608 respectively in the basic rocks, and from 0.70514-0.71161 to 0.512108-0.512526 respectively in the acid rocks. These chemical and isotopic differences between both types of magmatism are interpreted as a consequence of different degrees of crustal contamination from an enriched mantle source with a lithospheric component in an extensional intracontinental geodynamic setting followed by crystal fractionation to generate acid and basic melts. Geochemical and isotopic similarities between the Triassic basic rocks and the Lower Jurassic gabbros from the Limarí Complex in the Coastal Range in central Chile are interpreted as a consequence of a cogenetic event, related to the Mesozoic evolution of this portion of the Gondwana pacific margin. | en-US |
| dc.format | application/pdf | |
| dc.format | text/html | |
| dc.language | eng | |
| dc.publisher | Servicio Nacional de Geología y Minería | en-US |
| dc.relation | http://www.andeangeology.cl/index.php/revista1/article/view/V27n1-a06/695 | |
| dc.relation | http://www.andeangeology.cl/index.php/revista1/article/view/V27n1-a06/html | |
| dc.source | Andean Geology; Vol 27, No 1 (2000); 83-98 | es-ES |
| dc.source | Andean Geology; Vol 27, No 1 (2000); 83-98 | en-US |
| dc.source | 0718-7106 | |
| dc.source | 0718-7092 | |
| dc.title | Aporte cortical en la genesis del volcanismo bimodal Triasico de la Cordillera de la Costa, Chile central. | es-ES |
| dc.title | Crustal contribution in the genesis of the bimodal Triassic volcanism from the Coastal Range, central Chile | en-US |
| dc.type | info:eu-repo/semantics/article | |
| dc.type | info:eu-repo/semantics/publishedVersion | |
| dc.type | es-ES | |
| dc.type | en-US |
This item appears in the following Collection(s)
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Andean Geology
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