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Geochemical fingerprints of devolatilization reactions in the high pressure rocks of Ile de Groix, France

English title Geochemical fingerprints of devolatilization reactions in the high pressure rocks of Ile de Groix, France
Applicant Schmidt Susanne
Number 113280
Funding scheme Project funding
Research institution Département des sciences de la Terre Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Mineralogy
Start/End 01.10.2006 - 30.09.2008
Approved amount 110'240.00
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Keywords (5)

High pressure metamorphism; devolatilization reactions; subduction zone; stable isotope analysis; Ile de Groix

Lay Summary (English)

Lead
Lay summary
Subduction zones in convergent settings are geologically important sites which produce crust from sediments, oceanic crust, and mantle lithosphere and which play an important role in arc magmatism and volatile recycling processes. Physical, petrologic and thermal models for the evolution of subduction zones suggest that devolatilization reactions in the downgoing slab can generate large quantities of fluids during various stages of subduction.

Two models have been proposed for the devolatilization of subduction zones: “A single phase hydration model” where fluids migrate upward along the subduction zone and “a stepwise and continuous model”which postulates that dehydration of subduction zones is a combination of a stepwise and continuous processes and that a large portion of the H2O will be liberated at a relatively shallow level in the subduction zone.However, the mechanisms and the pathways by which these fluids are released are poorly constrained and have been discussed in various field areas.

This study deals with a particular aspect of devolatilization reactions in eclogite, glaucophane, amphibolite and greenschist facies rocks occurring on the Island of Groix (Brittany,France) and wants to examine the geochemical and petrological signatures of the high pressure rocks that devolatilization reactions have imprinted on these high pressure rocks. The study places a particular emphasis on the importance of fluids to the development of the metamorphic zones present and the significance of a ductile thrust during the devolatilization and exhumation of these rocks.
Direct link to Lay Summary Last update: 21.02.2013

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Number Title Start Funding scheme
121940 Geochemical fingerprints of devolatilization reactions in the high pressure rocks of Ile de Groix, France 01.10.2008 Project funding

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