Kinetics and mechanism of antigorite dehydration: Implications for subduction zone seismicity

摘要: Properties of serpentine minerals are thought to influence the occurrence and location intermediate‐depth seismicity in subduction zones, which is often characterized by two dipping planes separated ∼30 km defining a double seismic zone. The lower plane believed be provoked dehydration since experimentally determined stability limit for antigorite matches hypocenter locations. This requires that fluid produced released much faster than typical time scale ductile deformation mechanisms. Here we measured kinetics situ at high pressure temperature time‐resolved synchrotron X‐ray diffraction closed system. Antigorite dehydrates steps. During step 1 it partially breaks down into olivine hydrous phyllosilicate closely related 10 A phase. modal abundance intermediate assemblage described 66 wt % antigorite, 19 olivine, 12 2 higher temperature, remaining phase fully dehydrate. From analysis reaction progress data, major release aqueous occurs during fast rate 10−4 mfluid 3 mrock −3 s−1. exceeds orders magnitude mechanisms any mineral or rock subducting slab overlying mantle wedge. These results suggest may well trigger