Thermal decomposition of serpentine during coseismic faulting: Nanostructures and mineral reactions |
| |
Authors: | Cecilia Viti Takehiro Hirose |
| |
Institution: | 1. Earth Science Department, Siena University, Via Laterina 8, 53100 Siena, Italy;2. Kochi Institute for Core Sample Research, JAMSTEC, 200 Monobe-otsu Nankoku, Kochi 783-8502, Japan |
| |
Abstract: | This paper reports a detailed characterization of an antigorite-bearing serpentinite, deformed at seismic slip-rate (1.1 m/s) in a high-velocity friction apparatus. Micro/nanostructural investigation of the slip zone (200 μm thick) revealed a zonal arrangement, with a close juxtaposition of horizons with significantly different strength, respectively consisting of amorphous to poorly-crystalline phases (with bulk anhydrous composition close to starting antigorite) and of highly-crystalline assemblages of forsterite and disordered enstatite (200 nm in size and in polygonal-like nanotextures). The slip zone also hosts micro/nanometre sized Cr-magnetite grains, aligned at low angle with respect to the slipping surface and inherited from the host serpentinite.Overall observations suggest that frictional heating at asperities on the slipping surface induced a temperature increase up to 820–1200 °C (in agreement with flash temperature theory), responsible for serpentine complete dehydration and amorphization, followed by crystallization of forsterite and enstatite (under post-deformation, static conditions). The results of this study may provide important keys for the full comprehension of the mechanical behaviour and of the possible geodynamical role of serpentinite-hosted faults through the seismic cycle. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|