Mechanisms of the Creep-seismic Slip Transition along the Guanxian-Anxian Fault Zone,Longmen Shan:Evidence from the WFSD-3 CoreOA
The Guanxian-Anxian fault zone in the Longmen Shan,Sichuan,China,exhibits long-term creep-slip but ruptured during the 2008 Wenchuan earthquake,challenging the view that creeping faults rarely generate strong earthquakes.To investigate the transition from creep-slip to stick-slip,we analyzed fault rocks from the WFSD-3,using microstructural observations,XRD,μXRF,Raman spectroscopy,and quartz grain size statistics.Fault rocks show intense foliation,pressure-solution structures,and abundant clay minerals,reflecting long-term aseismic creep.At the interface between black and gray fault gouges at~1249.98 m,microstructures indicate stick-slip behavior,including truncated grains,angular fragments,and finer grain sizes.Here,clay content drops sharply while strong minerals(quartz,feldspar,calcite,dolomite)increase.Elemental mapping shows Al and K enriched in black gouge,whereas Ca and Si in gray gouge;Raman spectroscopy indicates possible graphitization;the finest quartz grains occur in black gouge.These features mark co-seismic principal slip zone of the Wenchuan earthquake.We propose that fluid-driven transformation of strong minerals into clays facilitates creep-slip,whereas localized precipitation of strong minerals strengthens the fault,causing stress accumulation and controlling the creep-slip to stick-slip transition.This mechanism has implications for reassessing seismic hazards of creeping faults.
LAI Ya;LI Haibing;SI Jialiang;LI Chunrui;WANG Huan;ZHANG Lei;SUN Zhiming;ZHANG Jinjiang
State Key Laboratory of Deep Earth and Mineral Exploration,Key Laboratory of Continental Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China School of Earth and Space Sciences,Peking University,Beijing 100871,ChinaState Key Laboratory of Deep Earth and Mineral Exploration,Key Laboratory of Continental Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,ChinaState Key Laboratory of Deep Earth and Mineral Exploration,Key Laboratory of Continental Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,ChinaState Key Laboratory of Deep Earth and Mineral Exploration,Key Laboratory of Continental Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,ChinaState Key Laboratory of Deep Earth and Mineral Exploration,Key Laboratory of Continental Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,ChinaState Key Laboratory of Deep Earth and Mineral Exploration,Key Laboratory of Continental Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,ChinaInstitute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,ChinaSchool of Earth and Space Sciences,Peking University,Beijing 100871,China
天文与地球科学
creep-slipstick-slipfault rocksmicrostructuregeochemistryGuanxian-Anxian fault zoneWenchuan earthquakeLongmen Shan
《Acta Geologica Sinica(English Edition)》 2026 (1)
P.231-250,20
supported by the National Natural Science Foundation of China(42230312,42272270,42172262,42372266)the Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project(2024ZD1000500)the China Geological Survey Project(DD20240041).
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