The Northern End of the Xiannvshan Fault at the Three Gorges Area

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摘要 TheXiannvshanfaultzone,lyingalongthewesternmarginoftheHuanglinganticline,isoneofthemostimportantfaultzonesintheThreeGorgesreservoirarea.ThefaultexperiencedstrongactivityduringtheCenozoicEra.ThequestionofwhetherthefaultzonegoesthroughtheYangtzeRiverhasbeenoneofthekeyproblemsfacedinpreviousstudiesasithasasignificantinfluenceupontheassessmentofgeologicalhazardsandearthquakestabilityinthereservoirarea.BasedontectonicandgeomorphicobservationsalongthefaultzonebetweentheBaixianchivillageinChangyangcountyandHuangkouvillageinZiguitown,togetherwiththecomparisonsbetweenthegeologyinGuizhouandQuyuantowninthenorthbankoftheYangtzeRiverandtheXiannvshanfaultzone,itissuggestedthatthenorthendofthisfaultzoneislocatedaroundHuangkouvillageanddoesnotgothroughtheYangtzeriversnorthward.Theevidenceisasfollows:①Onthebasisoffielddatacollection,itisfoundthattheXiannvshanFaultzone,whichstretches80km,underwentthrustmovementintheCenozoicperiod,resultinginravinesandfaultscarps,topographically.Whereas,onthenorthernbankoftheYangtzeRiver,faultsarerarelyfound,andmostofthefaultsaredevelopedintheJurassicstrata,withouttopographicaleffects.Therefore,theXiannvshanFaultzonehasnotstretchedtothenorthbankoftheYangtzeRiver.②ThefaultgougeandtectonitezonewerefounddevelopedontheXiannvshanFaultzoneatBaixianchivillage,butonlyatectonitezonewasfoundatZhoupingvillage.Therearealsosomebranchfaultsclosetothenorthernendofthefaultzone.So,theactivityofthefaultzoneweakenedfromsouthtonorthinCenozoic.ThefaultzoneextendsnorthwardanddiesoutatHuangkou.Itdoesn’tstretchforwardanylongerasindicatedbycontinuousstrata,sparsejoints,andsmallfolds,etc.
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出版日期 2012年04月14日(中国期刊网平台首次上网日期,不代表论文的发表时间)