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| DOI | 10.1016/J.LITHOS.2019.03.023 | ||||
| Año | 2019 | ||||
| Tipo | artículo de investigación |
Citas Totales
Autores Afiliación Chile
Instituciones Chile
% Participación
Internacional
Autores
Afiliación Extranjera
Instituciones
Extranjeras
This work provides the first comprehensive petrological and multi-scale structural investigation of a suite of ultramafic bodies and enclosing metasediments from the Late Paleozoic accretionary prism of South-Central Chile. The targeted outcrops are located in the La Cabana area and are characterized by the presence of three main types of ultramafic rocks: (1) partially serpentinized massive peridotites, (2) antigoritic schistose serpentinites, and (3) antigoritic mylonitic serpentinites. Partially serpentinized massive peridotites and schistose serpentinites recorded a common first hydration event with the formation of Fe2+ porous rim in chromites (at similar to 500 degrees C), followed by static partial transformation of olivine to lizardite (below similar to 300 degrees C) and formation of rims of Fe3+ rich chromite and magnetite around chromites. A second event of serpentinization linked to fluid passage through zones with focused deformation resulted in the partial transformation of partially lizarditized massive peridotites into antigoritic schistose serpentinites (at similar to 320-400 degrees C). This second event took place within the shallower portion of the serpentinitic subduction channel, near the base of the accretionary prism and was characterized by the formation of tubular folds made up of lenses of olivine-lizardite massive rocks embedded in a matrix of schistose serpentinites. Antigoritic mylonitic serpentinites encountered in the matrix of schistose serpentinites may locally contain metamorphic olivine (i.e., olivine-bearing mylonitic serpentinites), registering higher temperature conditions at medium pressures (similar to 600 degrees C, 11 kbar) that prevailed during the initial immature stage of development of the subduction system. Moreover, some mylonitic serpentinites containing Ti-clinohumite, Ti-chondrodite and metamorphic olivine still record higher pressure conditions (>15 kbar, i.e., >50 km depth for similar to 500 degrees C), which are related with a deformational event taking place when the subduction system had already cooled. These medium- and high-P mylonitic serpentinites preserved kinematic indicators of burial, whereas their exhumation along the subduction channel towards the shallower schistose serpentinites near the base of the accretionary prism could take place through discrete shear zones possibly aided by large sheath folds. Once incorporated in the accretionary prism (c. 285 Ma ago), the serpentinites shared metamorphism and deformation with the enclosing metasediments. Subvertical shortening related to uplift processes within the accretionary system took place in the stability field of antigorite (>300 degrees C) and, later, a subhorizontal E-W shortening prevailed in more superficial conditions. (C) 2019 Elsevier B.V. All rights reserved.
| Ord. | Autor | Género | Institución - País |
|---|---|---|---|
| 1 | Plissart, Gaelle | - |
Universidad Austral de Chile - Chile
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| 2 | GONZALEZ-JIMENEZ, JOSE MARIA | Hombre |
UNIV GRANADA - España
Universidad de Granada, Facultad de Ciencias - España |
| 3 | GARRIDO-CAYUPE, LEONARDO NICOLAS FABIAN | Hombre |
Universidad de Chile - Chile
Centro de Excelencia en Geotermia de Los Andes - Chile |
| 4 | Colas, Vanessa | Mujer |
Univ Nacl Autonoma Mexico - México
Universidad Nacional Autónoma de México - México |
| 5 | Berger, J. | Hombre |
Univ Toulouse - Francia
Université de Toulouse - Francia Universite Paul Sabatier Toulouse III - Francia Université Toulouse III - Paul Sabatier - Francia Géosciences Environnement Toulouse - Francia |
| 6 | Monnier, C. | Hombre |
Nantes Univ - Francia
Université de Nantes - Francia Université des Antilles - Francia Nantes Université - Francia |
| 7 | Diot, Herve | - |
Nantes Univ - Francia
La Rochelle Univ - Francia Université de Nantes - Francia Université de La Rochelle - Francia Université des Antilles - Francia Nantes Université - Francia La Rochelle Université - Francia |
| 8 | Padron-Navarta, Jose Alberto | Hombre |
Univ Montpellier - Francia
Univ Antilles - Francia Géosciences Montpellier - Francia Université des Antilles - Francia |
| Fuente |
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| Fondo Nacional de Desarrollo Científico, Tecnológico y de Innovación Tecnológica |
| Fondo Nacional de Desarrollo CientÃfico, Tecnológico y de Innovación Tecnológica |
| Fondecyt Iniciacion Grants |
| Agradecimiento |
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| The editors of Lithos are thanked for the final editing of this paper. Anonymous referees are also thanked for their constructive review of the paper. This work was supported by Fondecyt Iniciacion Grants (#11150635 and #11140005), and the RYC-2015-17596 to Jose Maria Gonzalez-Jimenez. We also acknowledge Laurent Lenta (University of Nantes) and Jesus Montes-Rueda (University of Granada) for their careful preparation of thin sections, Philippe De Parseval and Sophie Gouy (Centre de Microcaracterisation Raimond Castaing) for assistance of EMPA work, Yann Morizet (University of Nantes) for assistance during Raman analyses, Ricardo Silva for SEM analyses (UACh) and Loreto Troncoso for DRX assistance (UACh). |
| The editors of Lithos are thanked for the final editing of this paper. Anonymous referees are also thanked for their constructive review of the paper. This work was supported by Fondecyt Iniciación Grants (# 11150635 and # 11140005 ), and the RYC-2015-17596 to José Maria González-Jiménez. We also acknowledge Laurent Lenta (University of Nantes) and Jesús Montes-Rueda (University of Granada) for their careful preparation of thin sections, Philippe De Parseval and Sophie Gouy (Centre de Microcaractérisation Raimond Castaing) for assistance of EMPA work, Yann Morizet (University of Nantes) for assistance during Raman analyses, Ricardo Silva for SEM analyses (UACh) and Loreto Troncoso for DRX assistance (UACh). |