Magmatismo asociado a subduccion del Jurasico a Cretacico Inferior en la Cordillera de la Costa del norte de Chile (18°30'-24°S): geoquimica y petrogenesis.
Jurassic to Early Cretaceous subduction-related magmatism in the Coastal Cordillera of northern Chile (18°30'-24°S): geochemistry and petrogenesis
| dc.contributor | en-US | |
| dc.contributor | es-ES | |
| dc.creator | Oliveros, Veronica | |
| dc.creator | Morata, Diego | |
| dc.creator | Aguirre, Luis | |
| dc.creator | Feraud, Gilbert | |
| dc.creator | Fornari, Michel | |
| dc.date | 2010-06-24 | |
| dc.identifier | http://www.andeangeology.cl/index.php/revista1/article/view/V34n2-a03 | |
| dc.identifier | 10.5027/andgeoV34n2-a03 | |
| dc.description | En la Cordillera de la Costa del norte de Chile, el magmatismo del Jurasico y Cretacico Inferior esta representado por potentes secuencias de rocas volcanicas y volcanoclasticas, principalmente de composicion intermedia, y rocas sedimentarias. Ellas estan intruidas por grandes plutones, ademas de diques e intrusivos menores. En este trabajo se presentan nuevos datos geoquimicos, de elementos mayores y traza, correspondientes a un grupo de rocas volcanicas y plutonicas del Jurasico Medio a Superior recogidas en seis localidades en la Cordillera de la Costa del norte de Chile (18°30'-24°S). Las rocas volcanicas son bastante homogeneas en sus caracteristicas petrograficas y geoquimicas y corresponden a lavas porfiriticas de composicion basaltico-andesitica a andesitica, de afinidad calcoalcalina a calcoalcalina de alto-K, presentando mayor abundancia de elementos LIL con respecto a elementos HFS y anomalias negativas de Nb y Ti. Todos estos rasgos geoquimicos son tipicos de rocas generadas en ambientes de subduccion. No se observan diferencias significativas entre rocas volcanicas de distintas regiones o edades. Sin embargo, las rocas plutonicas presentan patrones de REE mas planos, levemente mas enriquecidos o empobrecidos, con respecto a los de las rocas volcanicas. La evolucion y diferenciacion de los magmas parentales se debio principalmente a la cristalizacion fraccionada de plagioclasa, olivino y clinopiroxeno sin una asimilacion importante de corteza continental. Sin embargo, los contenidos de La y Th indicarian un aumento de la contribucion de los sedimentos subductados en la genesis de los magmas o un aumento del grado de contaminacion cortical con el tiempo. La fuente magmatica fue posiblemente un manto deprimido, posteriormente metasomatizado por fluidos provenientes de la deshidratacion de la placa subducida. No se encontraron evidencias geoquimicas de fusion de la corteza oceanica en las rocas estudiadas. El regimen tectonico extensional que domino la evolucion del arco magmatico del Jurasico y Cretacico Inferior en el norte de Chile habria favorecido la extrusion de grandes volumenes de rocas volcanicas en un periodo de tiempo relativamente corto, evitandose asi la interaccion de los magmas con la corteza continental. | es-ES |
| dc.description | Jurassic to Early Cretaceous magmatism in the Coastal Cordillera of northern Chile is represented by thick sequences of mostly basaltic-andesitic to andesitic lava flows and minor sedimentary rocks. The volcanic sucession was intruded by large plutonio bodies and smaller stocks and dikes. New geochemical data, including major and trace elements for a suite of Middle to Upper Jurassic volcanic and plutonio rocks from six localities in the Coastal Cordillera (18°30'-24°S), are presented here. The volcanic rocks are characterized by their petrological and chemical homogeneity; they are highly porphyritic basaltic-andesites and andesites with calc-alkaline to high-K calc-alkaline affinities, higher LILE than HFSE abundances, negative Nb and Ti anomalies, and LREE/HREEfractionation, which are the typical compositional features of subduction-related igneous rocks. No significant differences are observed in rocks from different areas or ages, but the plutonio rocks show subparallel, less and more enriched patterns respectively compared to volcanic rocks. The evolution and differentiation of the parental magmas is mainly due to fractional crystallization dominated by plagioclase, olivine and clinopyroxene. Assimilation of the continental crust was not important, although Th and La contents would indicate increasing sediment contribution or crustal contamination of the magmas with time. The magma source is likely to be a depleted mantle metasomatized by fluids, which originated from dehydration of the subducted oceanic crust. No evidence of slab melting was found in the studied rocks. The extensional tectonic setting that dominated the evolution of the Jurassic-Early Cretaceous arc in northern Chile would have favoured the extrusion of huge amounts of volcanic rocks during a relatively short period of time, avoiding thus a mayor interaction with the continental crust. | 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/V34n2-a03/490 | |
| dc.relation | http://www.andeangeology.cl/index.php/revista1/article/view/V34n2-a03/html | |
| dc.source | Andean Geology; Vol 34, No 2 (2007); 209-232 | es-ES |
| dc.source | Andean Geology; Vol 34, No 2 (2007); 209-232 | en-US |
| dc.source | 0718-7106 | |
| dc.source | 0718-7092 | |
| dc.title | Magmatismo asociado a subduccion del Jurasico a Cretacico Inferior en la Cordillera de la Costa del norte de Chile (18°30'-24°S): geoquimica y petrogenesis. | es-ES |
| dc.title | Jurassic to Early Cretaceous subduction-related magmatism in the Coastal Cordillera of northern Chile (18°30'-24°S): geochemistry and petrogenesis | 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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