Quantitative texture analysis of talc in mantle hydrated mylonites

Wednesday, 17 December 2014
Jose Manuel Benitez-Perez1, Juan Gomez Barreiro1, Hans-Rudolf Wenk2, Sven C Vogel3, Yusuke Soda4, Marco Voltolini5 and Jose R Martinez-Catalan1, (1)University of Salamanca, Salamanca, Spain, (2)Univ California Berkeley, Berkeley, CA, United States, (3)Los Alamos National Laboratory, Los Alamos, NM, United States, (4)Kanazawa University, Ishikawa, Japan, (5)Lawrence Berkeley National Laboratory, Berkeley, CA, United States
A quantitative texture analysis of talc-serpentinite mylonites developed in highly deformed ultramafic rocks from different orogenic contexts have been done with neutorn diffraction at HIPPO (Los Álamos National Laboratory). Mineral assemblage, metamorphic evolution and deformative fabric of these samples could be correlated with those verified along the shallow levels (<100km; <5GPa) of a subduction zone. The hydration of mantle (ultramafic) rocks at those levels it is likely to occur dynamically, with important implications on seismogenesis. Given the high anisotropy of the major phases in the samples (i.e. talc and antigorite) it is expected to influence seismic anisotropy of the whole system, in the presence of texture. However to date there was no data on the crystallographic preferred orientation of talc and examples of antigorite textures are very limited. We explore the contribution of talc texture to the seismic anisotropy of mantle hydrated mylonites.

Acknowledgements: This work has been funded by research project CGL2011-22728 of Spanish Ministry of Economy and Competitiveness. JGB and JMBP are grateful to the Ramón y Cajal and FPI funding programs. Access to HIPPO (LANSCE) to conduct diffraction experiments is kindly acknowledged.