The aim of the project is to understand the role of metamorphic fluid release on the generation of intermediate-depth seismicity by the study of eclogite-facies blocks from the eastern Monviso shearzone, interpreted in previous works as the result of seismic rupture planes (see, i.e., Angiboust et al., 2012).

The Monviso meta-ophiolite complex (Northern Italy, Western Alps) represents a coherent portion of oceanic lithosphere metamorphosed during the Alpine orogeny at eclogite facies peak conditions (2.6 GPa - 550C, Lago Superiore Unit, Angiboust et al., 2011). In this optic, found eclogite breccias and (potentially) pseudotavhylites represent a unique opportunity to study first-hand "frozen" earthquake-derived rocks from 80 Km depth!

To understand the significance of these eclogite breccias, a multi-methodologic approach is adopted; the work-flow is thought to study the brecciation development from the macro to the micro scale, zooming inside the processes controlling intermediate depth seismicity.

At first level the project lead by geological mapping of the eastern side of Monviso Metaophiolite with the characterization of eclogite breccias and other eclogitic blocks. Field work is essential to correctly define the occurrence of blocks and their link to the geology of the area, which records multiple deformative stages from eclogitic to late-alpine greenschists facies.

The characterization of distribution, recurrence and morphological characteristics of breccia blocks is the subsequent step, necessary to focus on the processes driving the deformation at peak eclogitic condition.

On rocks samples (many of them collected with a corer) is currently developed a complex set of analysis as Microprobe, SEM, XRF, LA-ICP-MS and potentially EBSD. The aim is to reveal the microstructural, petrographic and geochemical processes driving eclogite breccias formation.

The key-points are to understand if brecciation was triggered by external fluid influx or local dehydration, what was the reaction order and what was the stress’s effect on rock’s brecciation. Another focal point is to define if rocks record one or more brecciation events and, in case of positive answer, describe a relative-chronology of brecciation distinguishing the different budgets and chemical characteristics of fluids input/release. The structural and petrographic analysis of blocks and the surrounding shearzone’s matrix will give new insights on the evolution of Monviso meta-ophiolite complex.