Geological Society of America;Boulder: Geological Society of America (GSA)
摘要:
摘要： The Longmenshan fault that ruptured during the 2008 Mw 7.9 Wenchuan (China) earthquake was drilled to a depth of 1200 m, and fault rocks including those in the 2008 earthquake slip zone were recovered at a depth of 575-595 m. We report laboratory strength measurements and microstructural observations from samples of slip zone fault rocks at deformation conditions expected for coseismic slip at borehole depths. Results indicate that the Longmenshan fault at this locality is extremely weak at seismic slip rates. In situ synchrotron X-ray diffraction analysis indicates that graphite was formed along localized slip zones in the experimental products, similar to the occurrence of graphite in the natural principal slip zone of the 2008 Wenchuan rupture. We surmise that graphitization occurred due to frictional heating of carbonaceous minerals. Because graphitization was associated with strong dynamic weakening in the experiments, we further infer that the Longmenshan fault was extremely weak at borehole depths during the 2008 Wenchuan earthquake, and that enrichment of graphite along localized slip zones could be used as an indicator of transient frictional heating during seismic slip in the upper crust. 出版者： Boulder: Geological Society of America (GSA) 出版日期： 2014-01-01 出處： Geology, 2014-01, Vol.42 (1), p.47-50 資源來源： GeoScienceWorld 版權： GeoRef, Copyright 2020, American Geosciences Institute. Reference includes data from GeoScienceWorld Alexandria, VA USA United States. Reference includes data supplied by the Geological Society of America Boulder, CO USA United States 版權： Copyright Geological Society of America Jan 2014 識別號： ISSN: 0091-7613 識別號： EISSN: 1943-2682 識別號： DOI: 10.1130/G34862.1
