Early Andean tectonomagmatic stages in north Patagonia: insights from field and geochemical data
| Autor: | Christian Creixell, Andrés Folguera, Andrés Echaurren, Friedrich Lucassen, Federico Ibarra, Verónica Oliveros |
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| Rok vydání: | 2017 |
| Předmět: |
TECTONICS
geography geography.geographical_feature_category 010504 meteorology & atmospheric sciences Earth science Geochemistry Geology 010502 geochemistry & geophysics 01 natural sciences Unconformity Cretaceous Ciencias de la Tierra y relacionadas con el Medio Ambiente Petrography Volcanic rock PATAGONIA Batholith Magmatism Geología Sedimentary rock ANDES Foreland basin FOLD-THRUST BELT CIENCIAS NATURALES Y EXACTAS 0105 earth and related environmental sciences |
| Zdroj: | Journal of the Geological Society. 174:405-421 |
| ISSN: | 2041-479X 0016-7649 |
| DOI: | 10.1144/jgs2016-087 |
| Popis: | The Andes in northern Patagonia are mainly formed by Mesozoic magmatic units: the mostly Jurassic-Cretaceous North Patagonian Batholith and volcanism of the Jurassic Lago La Plata (Ibáñez) Formation as well as the mid-Cretaceous Divisadero Group. These rocks represent the development of a magmatic belt through Jurassic-mid-Cretaceous time, during a switch of the tectonic regime from extension to compression. To study arc evolution during this transition, we carried out fieldwork and geochemical sampling at c. 43°S, clarifying structural relationships and characterizing the magmatic sources. Multi-element diagrams for both volcanic units suggest a slab-derived signature, whereas isotopic ratios (Sr-Nd-Pb) indicate parental melts sourced from the subduction-modified asthenospheric mantle interacting with crustal sources during their emplacement. An angular unconformity is identified between the synextensional Jurassic volcanic rocks and Lower Cretaceous sedimentary rocks beneath the mid-Cretaceous sequences. Although this deformational event was simultaneous with generalized overriding plate compression, geochemical ratios indicate an immature Aptian-Albian arc with no associated crustal thickening. Late Jurassic to mid-Cretaceous arc settlement after a trenchward retraction of magmatism from the foreland between c. 41 and 45°S, with an associated increase in slab dip angle, may have provoked crustal softening facilitating the subsequent initial fold-thrust belt growth. Fil: Echaurren Gonzalez, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Oliveros, Verónica. Universidad de Concepción; Chile Fil: Folguera Telichevsky, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Ibarra, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Creixell, Christian. Servicio Nacional de Geología y Minería; Chile Fil: Lucassen, Friedrich. Universitat Bremen; Alemania |
| Databáze: | OpenAIRE |
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