305 Subduction Zone Processes: Insights from Geology, Geochemistry, and Petrochronology (Posters)

We invite contributions that explore the geologic processes of subduction zones from new field observations, analytical methodologies, and numerical modeling of metamorphic rocks along the subduction interface or try to integrate or reconcile the rocks record with geophysical observations.

Wednesday, 22 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Petrographic and Microstructural Investigation of the Queyras Gabbros: Assessing the Influence of Fe-Ti Oxides on Pyroxene and Plagioclase Deformation

Paper number: 305-8
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Gabbroic rocks are the most abundant rock in the oceanic and lower continental crusts, both of which play a crucial role in many geodynamic processes such as plate tectonics, mid-ocean ridge formation, and the subduction cycle. Yet, their rheology remains poorly understood. In this study, we aim to constrain the mechanical evolution and strain localization processes of grabbro at the brittle-ductile transition. We focus our analysis on three sites located in the Queyras Massif (French Alps) that represent well-preserved fragments of the Tethyan oceanic lithosphere interpreted to have formed along a slow-spreading ridge. The origin of these gabbros has been interpreted to be an oceanic core complex before subduction and exhumation during the alpine orogeny. We present the results of a detailed petrological and microstructural analysis of the pyroxene, plagioclase, and Fe-Ti oxides on our gabbros samples. Future findings from this research will improve current models of plate dynamics, mid-oceanic ridge and oceanic core complex formation, and subduction processes.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412522

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