Comparative Mineralogical and Geochemical Compositions within the Fault Gouge in the Surface Exposures of the Mw7.9 Wenchuan Earthquake Fault and Their Implications for Mass Removal and Fluid-Rock Interactions  

作　　者：Yangyang Wang Sijia Li Shiyuan Wang Deyang Shi Weibing Shen 

机构地区：[1]National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China [2]Geological Exploration and Development Research Institute,Chuanqing Drilling Engineering Co.,Ltd.,CNPC,Chengdu 610500,China [3]Sichuan Earthquake Agency,Chengdu 610041,China [4]Institute of Geophysics,China Earthquake Administration,Beijing 100081,China [5]MLRKey Laboratory of Isotope Geology,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China

出　　处：《Journal of Earth Science》2025年第1期266-274,共9页地球科学学刊(英文版)

基　　金：supported by the research grant from Institute of Crustal Dynamics,China Earthquake Administration(No.ZDJ2019-02)。

摘　　要：Geochemistry of the fault gouge record information on fault behaviors and environmental conditions.We investigated variations in the mineralogical and geochemical compositions of the fault gouge sampled from the margin zone(MZ)to the slip central zone(CZ)of the fault gouge in the Beichuan-Yingxiu surface rupture zone of the Wenchuan Earthquake.Results show that the clay minerals contents increase from the MZ to CZ,and the quartz and plagioclase contents slight decrease.An increasing enrichment in Al_(2)O_(3),Fe_(2)O_(3),and K_(2)O are observed toward the CZ;the decomposition of quartz and plagioclase,as well as the depletion of Si O_(2),Ca O,Na_2O,and P_(2)O_(5)suggest that the alkaline-earth elements are carried away by the fluids.It can be explained that the stronger coseismic actions in the CZ allow more clay minerals to form,decompose quartz and plagioclase,and alter plagioclase to chlorite.The mass loss in the CZ is larger than that in MZ,which is maybe due to the more concentrated stress in the strongly deformed CZ,however other causes will not be excluded.

关 键 词：fault gouge mass transfer fluid-rock interactions geochemical transformation Wenchuan Earthquake 

分 类 号：P315[天文地球—地震学]