摘要
ThispaperreportstheinternalstructuresoftheBeichuanfaultzoneofLongmenshanfaultsystemthatcausedthe2008Wenchuanearthquake,atanoutcropinHongkou,Sichuanprovince,China.PresentworkisapartofcomprehensiveprojectofInstituteofGeology,ChinaEarthquakeAdministration,tryingtounderstanddeformationprocessesinLongmenshanfaultzonesandeventuallytoreproduceWenchuanearthquakebymodelingbasedonmeasuredmechanicalandtransportproperties.Outcropstudiescouldbeintegratedwiththoseperformedonsamplesrecoveredfromfaultzonedrilling,duringtheWenchuanEarthquakeFaultScientificDrilling(WFSD)Project,tounderstandalong-faultanddepthvariationoffaultzoneproperties.Thehangingwallsideofthefaultzoneconsistsofweakly-foliated,clayeyfaultgougeofabout1minwidthandofseveralfaultbrecciazonesof30-40mintotalwidth.Wecouldnotfindanypseudotachyliteatthisoutcrop.DisplacementduringtheWenchuanearthquakeishighlylocalizedwithinthefaultgougelayeralongnarrowerslipping-zonesofabout10to20mminwidth.Thisisanimportantconstraintforanalyzingthermalpressurization,animportantdynamicweakeningmechanismoffaults.Overlappingpatternsofstriationsonslickensidesurfacesuggestthatseismicslipatagiventimeoccurredinevennarrowerzoneofafewtoseveralmillimeters,sothatlocalizationofdeformationmusthaveoccurredwithinaslippingzoneduringcoseismicfaultmotion.Faultbrecciazonesareboundedbythinblackgougelayerscontainingamorphouscarbon.Faultgougecontainsilliteandchloriteminerals,butnotsmectite.Clayeyfaultgougenexttocoseismicslippingzonealsocontainsamorphouscarbonandsmallamountsofgraphite.ThestructuralobservationsandmineralogicaldataobtainedfromoutcropexposuresofthefaultzoneoftheWenchuanearthquakecanbecomparedwiththoseobtainedfromtheWFSD-1andWFSD-2boreholes,whichhavebeendrilledveryclosetotheHongkououtcrop.Thepresenceofcarbonandgr
出版日期
2011年03月13日(中国期刊网平台首次上网日期,不代表论文的发表时间)