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时间:2020-03-08
《昔格达组地层研究中需要注意的若干关键问题_徐则民.pdf》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、第18卷第5期地学前缘(中国地质大学(北京);北京大学)Vol.18No.52011年9月EarthScienceFrontiers(ChinaUniversityofGeosciences(Beijing);PekingUniversity)Sep.2011昔格达组地层研究中需要注意的若干关键问题徐则民1,刘文连21.昆明理工大学土木系,云南昆明6502242.中国有色金属工业昆明勘察设计研究院,云南昆明6500511,LiuWenlian2XuZemin1.DepartmentofCivilEngineering,Kunm
2、ingUniversityofScienceandTechnology,Kunming650224,China2.KunmingNon-ferrousMetalReconnaissanceandDesignInstitute,Kunming650051,ChinaXuZemin,LiuWenlian.SomeproblemsinthestudyofthegenesisofXigedaFormation.EarthScienceFrontiers,2011,18(5):256-270Abstract:Theverticalsup
3、erimpositionrelationshipbetweentheXigedaFormationanditsoverlying,underlyingfluvi-algravellayersisofgreatsignificanceforindicatingsedimentaryenvironment.TheXigedaFormation,whichismain-lymadeofhorizontallylaminatedmottledfine-graineddepositsoftencontainingsandwichesof
4、tensofcentimetersoffluvialgravellayers,andthesiltlayersfrequentlycontaincross-beddingandcross-lamination.Thefluvial-lacustrinecharacteristicsandthebottomcurrentsinXigedalakesshouldbetakenintoaccountinthestudyofthegenesisoftheformation.ThemineralcomponentsofXigedafin
5、e-graineddepositsandtherocktypesofgravellayerswithinXigedaFormationchangewiththegeographiclocationsofoutcrops.Contemporaneousdeformationstructuresandfaultsde-velopinsomeXigedaFormationdistributionregions.Xigedaoutcropsarescatteredatthesouth-eastmarginofQing-hai-Tibe
6、tplateau,buthighlydependonthecurrentriversystems,eithertrackingsomemasterstreamanditstributa-riestoformbranchystructuresoronlydistributingalongthemasterstreamtoformrod-likestructures,whichsug-geststhatXigedaFormationdepositedaftercurrentriversystemhadarisenandhasage
7、neticrelationwiththeriversystems.ThehighestheightdifferenceamongXigedaoutcropsisupto2290mandthereareoftenoutcropelevationjumpsamongdifferentXigedaFormationdistributionregions.XigedaFormationdepositedprimarilyinlandslide-dammedlakes;secondlyinsagpondsderivedfromlocal
8、subsidenceofrivers,whichdevelopedalongthefaultzone.Keywords:XigedaFormation;fluvial-lacustrinedeposit;contemporaneousstructure;geologicals
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