Academic Journal
Mantle Wedge (De) formation During Subduction Infancy: Evidence from the Base of the Semail Ophiolitic Mantle
| العنوان: | Mantle Wedge (De) formation During Subduction Infancy: Evidence from the Base of the Semail Ophiolitic Mantle |
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| المؤلفون: | Prigent, Cécile, Agard, Philippe, Guillot, Stéphane, Godard, Marguerite, Dubacq, Benoît |
| المساهمون: | Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement IRD : UR219-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), ANR-10-BLAN-0615,O:NLAP,Obduction : la fin d'une énigme géodynamique ?(2010), ANR-10-LABX-0056,OSUG@2020,Innovative strategies for observing and modelling natural systems(2010), ANR-11-BS04-0014,TERRE,Transport électronique en régime relativiste dans des plasmas denses(2011), ANR-11-BSV4-0001,PARIS,Plasticité, assemblage et régulation du segment Initial de l'axone(2011), ANR-13-BS06-0012,DSP-Tibet,Etude des Processus profonds et de surface dans le Tibet Central(2013) |
| المصدر: | ISSN: 0022-3530. |
| بيانات النشر: | HAL CCSD Oxford University Press (OUP) |
| سنة النشر: | 2018 |
| المجموعة: | Université Savoie Mont Blanc: HAL |
| مصطلحات موضوعية: | fluid-peridotite interaction, mantle wedge, metasomatism, Semail ophiolite, subduction plate interface, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography |
| الوصف: | International audience ; The basal mantle of the Semail ophiolite directly overlying the metamorphic sole has been affected by a late and relatively low temperature ductile deformation event, ascribed to the deformation of the mantle just above the plate interface during subduction infancy (which ultimately led to ophiolite obduction). We show that this deformation results in the formation of proto-mylonitic (∼850–750°C) to ultra-mylonitic (∼750–650°C) shear zones wrapping lenses of porphyroclastic tectonites deformed at higher temperature (∼1200°C). In proto- to ultra-mylonites, syn-deformation hydrous fluid/peridotite interaction triggered the dissolution of coarser grains (olivine1, orthopyroxene1 and clinopyroxene1) and the crystallization of polymineralic mixtures of smaller grains (olivine2, orthopyroxene2, clinopyroxene2, spinel2 ± sulfide, together with magnesio-hornblende to pargasitic amphibole). This modal metasomatism is associated with cryptic metasomatism marked by striking mineral enrichment in some fluid-mobile-elements (especially B and Li). From the major and trace elements composition of the newly precipitated grains and estimated conditions of fluid/peridotite interaction (∼800°C), we interpret the metasomatic agent as a fluid derived from the dehydration of the amphibolitic to granulitic metamorphic sole (i.e. the metamorphosed crust from the downgoing plate) underlying the mantle during incipient subduction. We propose that this high temperature sole was accreted to the proto-mylonitic banded unit while dehydrating and that both units were exhumed together during peridotite ultra-mylonitic deformation, thereby preserving a fossilized warm subduction interface and evidence of an incipiently (de)forming mantle wedge. |
| نوع الوثيقة: | article in journal/newspaper |
| اللغة: | English |
| DOI: | 10.1093/petrology/egy090 |
| الاتاحة: | https://hal.science/hal-02005524 https://doi.org/10.1093/petrology/egy090 |
| رقم الانضمام: | edsbas.FF2C552D |
| قاعدة البيانات: | BASE |
| DOI: | 10.1093/petrology/egy090 |
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