Blueschist from the Toudaoqiao Area, Inner Mongolia, NE China: Evidence for the Suture between the Ergun and the Xing'an Blocks

(整期优先)网络出版时间:2017-02-12
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BlueschistaccompaniedbypeliticschistexposealongtheXinlin-XiguitufaultintheToudaoqiaoarea,northeasternChina.Inthispaper,theblueschistissystematicallystudiedonthepetrographyandmineralchemistry.Theamphibolesintheblueschistarezonedfromwinchitecoretomagnesioriebeckite/glaucophanerimtowinchiteoutermostrim.Thepeakmetamorphicconditionsaredefinedbythemineralassemblageofmagnesioriebeckite/glaucophane,epidote,high-Siphengite(Si<7.1),chlorite,albite,hematiteandquartz,indicatinganepidote-blueschistfaciesmetamorphism.TheP-TconditionsareestimatedasT=350–400℃andP=10-12kbar.TheoccurrenceoftheblueschistalongtheXinlin-XiguitufaultstronglysuggeststhefaultisthesuturebetweentheErgunandtheXing'anblockssituatedintheeasternportionsoftheCentralAsiaOrogenicBelt(CAOB).