简介：TheWahongshanfaultzoneinQinghaiprovinceisoneofthemostimportantfaultsinwesternChina.Inthispaper,deformationandX-raypetrofabricshavebeenstudiedinthemiddlesegmentofthefault.Theresultsshowthattheformationofthefaultzonescanbedividedintotwomajorstages:ductilesheardeformationstageandbrittledeformationstage.TheearlystageductileshearingleadstotheformationoftheNW-NNWtrendingmylonitezonesalongthefault,whichisintenselycutbythelate-formedbrittlefaults.X-raypetrofabricsofrocksnearthefaultsindicatethatthemineralsinthetectonitesshowagreatdegreeoforientationinthealignment.Thequartz,whichisaveryimportantmineralinthetectonites,isdeformedbybasalfaceglidingornearbasalfacegliding,andsometimesbyprismaticfacesliding,whichindicatesthattherocksaredeformedinepithermaltomesothermalormesothermalenvironment,andthedynamicrecrystallizationalsoplaysanimportantroleintheformationofthequartzalignment.TheresultsalsodemonstratethatplutonsformedintheHercynianandIndosinianstagesshownogreatductiledeformationascanbeseenfromtheX-raypetrofabrics,soitisconcludedthattheserocksareformedaftertheformationoftheductileshearzones.ResultsofStructuraldeformationanalysisandisotopegeochronologicanalysisofsyntectonicmuscoviteindicatethatWahongshanductileshearzonesareformedinthelateSilurianPeriodduringthelateCaledonianstage.