羌塘盆地胜利河地区雀莫错组地层及其古环境  

Stratigraphy and paleoenvironment of the Quemo Co Formation in Shengli River area,northern Tibet

作　　者：付修根[1] 王剑[1] 吴滔 何江林[1] 

机构地区：[1]成都地质矿产研究所,四川成都610081 [2]贵州省地质调查院,贵州贵阳550004

出　　处：《中国地质》2010年第5期1305-1312,共8页Geology in China

基　　金：国家自然科学基金项目(40702020);四川省青年科技基金项目(09ZQ026-006);国家油气专项"青藏高原重点盆地油气资源战略选区调查与选区"项目(XQ-2009-01)共同资助

摘　　要：在羌塘盆地胜利河地区实测了多条雀莫错组地层剖面,在区块南部剖面中采集到大量的硅化木以及一定含量的双壳类Astarte delicata Fan,A.cf.voltzii Goldfuss,Pleuromya sp.,Protocardia sp.,Modiolus sp.,Neomiodon sp.,Chlamys sp.等和孢粉化石Cyathidites,Deltoidospora,Neoraistrickia,Classopollis等。雀莫错组地层之下广泛沉积了一套那底岗日组火山-火山碎屑沉积,其火山岩喷发年龄为205～220Ma。雀莫错组地层之上与中侏罗统布曲组整合接触,依据上述特征确定了雀莫错组地层的时代为早-中侏罗世。雀莫错组地层沉积早期,以冲积扇-辫状河砾岩沉积为特征,之上沉积了一套三角洲相碎屑岩地层及局限台地相灰岩沉积,表现为一个向上变深的海侵序列。雀莫错组沉积期,胜利河地区处于偏潮湿的热带-亚热带环境。Recently abundant silicified wood was discovered in the Quemo Co Formation along the Shengli River section in Shengli River area,northern Tibet.In addition,certain amounts of bivalves（e.g.,Astarte delicata Fan,A.cf.voltzii Goldfuss,Pleuromya sp.,Protocardia sp.,Modiolus sp.,Neomiodon sp.,and Chlamys sp.）,spores and pollen grains（e.g.,Cyathidites,Deltoidospora,Neoraistrickia and Classopallis） were also found in this section.A detailed investigation along the section was performed to reconstruct the paleoenvironment during Quemo Co deposition.The magma emplacement age of the Nadi Kangri volcanic rocks underlying the Quemo Co Formation is ca.205-220 Ma,representing the early sedimentary age of the Quemo Co Formation.The Quemo Co strata are overlain conformably by the middle Jurassic Buqu strata.Therefore,the sedimentary age of the Quemo Co Formation should be early-middle Jurassic.The Quem Co Formation is composed chiefly of quartz sandstone and conglomerate intercalated with minor micritic limestone.The basal units are typically conglomeratic with the characteristics of alluvial and fluvial sedimentation.These units are overlain by quartz sandstone intercalated with micritic limestone containing salt,brackish and fresh water bivalve fossils,thus considered to be a delta environment.Subsequently,these strata were overlain by restricted platform limestone,indicating a progradational sequence of transition from continental to marine facies.The composition of palynofloras from Quemo Co strata suggests that the climate of the Shengli River region belonged to a sub-humid tropical to sub-tropical zone during the deposition of silicified wood.

关 键 词：沉积环境 古气候 雀莫错组 羌塘盆地 

分 类 号：P534.52[天文地球—古生物学与地层学]