青藏高原中南部前寒武系及古生界岩石地层组成和时代特征  

Precambrian-Paleozoic strata and their ages in the central and southern Tibetan Plateau

作　　者：张予杰 张以春[2] 王冬兵 苟正彬 ZHANG Yujie;ZHANG Yichun;WANG Dongbing;GOU Zhengbin(Chengdu Center,China Geological Survey(Southwest China Innovation Center for Geosciences),Chengdu 610081,Sichuan,China;State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing 210008,Jiangsu,China)

机构地区：[1]中国地质调查局成都地质调查中心(西南地质科技创新中心),四川成都610081 [2]现代古生物和地层学国家重点实验室,中国科学院南京地质古生物研究所,生物演化与环境卓越创新中心,江苏南京210008

出　　处：《地质通报》2021年第11期1814-1835,共22页Geological Bulletin of China

基　　金：第二次青藏高原综合科学考察研究(编号:2019QZKK0706);中国地质调查局项目《中尼铁路(境内段)沿线区域地质调查》(编号:DD20211195);国家自然科学基金重大研究计划重点项目《拉萨地块与相邻地块二叠纪古生物地理对比研究》(批准号:91855205);中国科学院战略性先导科技专项(B类)(编号:XDB26000000)。

摘　　要：对青藏高原中南部北羌塘、南羌塘、冈底斯、仲巴、喜马拉雅和昌都6个地区前寒武系及古生界岩石地层的组成和时代特征进行分析,总结了117个群组级岩石地层单位的岩性组合和时代特征,梳理地层划分对比中存在的相关问题。通过调查认为,前人划定的前寒武纪基底大多不再具有典型的变质或结晶基底特征,北羌塘可能具有相对稳定的基底,下古生界包括部分奥陶系和志留系,上古生界不整合在下古生界之上,发育早泥盆世晚期地层及中—上泥盆统、上石炭统和二叠系。南羌塘地区基底性质不明,下古生界以“残块”形式出露在玛依岗日一带,上古生界在南羌塘地区西部和东部一带表现样式不同,在西部日土一带具稳定沉积特点,东部双湖一带为“基质+块体”的俯冲增生杂岩。冈底斯地区,拉萨地块(中部)和聂荣微地体具前寒武纪基底,新元古代末—寒武纪发育一套“双峰式”火山岩,奥陶系可能不整合在前奥陶系之上,奥陶纪—二叠纪均为海相(或海陆过渡相)沉积。仲巴微地体自下而上可由上震旦系—寒武系片岩构造层、奥陶系—泥盆系变质碳酸盐岩构造层、石炭系—二叠系构造层组成。喜马拉雅地区具有较稳定的前寒武系结晶基底,中奥陶世—晚二叠世均沉积一套海相地层。昌都地区可能存在前寒武系基底,下古生界仅零星出露下奥陶统和志留系,上古生界除乐平统与瓜德鲁普统之间为假整合接触外,其余均为较连续的海相沉积地层。This paper summarizes the composition and age characteristics of the Precambrian and Paleozoic lithostratigraphy in the central to southern Qinghai-Tibet Plateau in six regions:the North Qiangtang area,the South Qiangtang area,the Gangdise area,the Zhongba area,the Himalaya and the Qamdo area.It summarizes the lithological and geochronological characteristics of 117 lithostratigraphic units,meanwhile,preliminarily sorts out the problems in stratigraphic division and correlation,so as to provide basic geological information for the pre-Mesozoic geological evolution of Qinghai-Tibet Plateau.The Qiangtang was considered that most of the Precambrian basement designated by predecessors no longer has typical metamorphic or crystalline basement characteristics.The northern Qiangtang area(with limited information)may have a relatively stable basement.Lower Paleozoic in northern Qiangtang area only includes part of the Ordovician and Silurian,and the Upper Paleozoic may be unconformity above the Lower Paleozoic;late Early Devonian,middle Late Devonian,Late Carboniferous and possibly the whole Permian develop successively.The basement in southern Qiangtang area is of unknown nature.The Lower Paleozoic in southern Qiangtang area is only exposed in the form of"residual block"in the Mayigangri mountain.And its Upper Paleozoic has different styles in the West and East:Rutu county area in the western has more stable sedimentary characteristics,while the Shuanghu area in the Eastern may be a subduction accretion complex of"matrix+block".In Gangdise area,except Lhasa block(central part)and Nerong block,the basement of other areas is unknown.A set of"bimodal"volcanic rocks developed from the end of Neoproterozoic to Cambrian in Gangdise area.The Ordovician may be unconformity above the pre-Ordovician in Gangdise area,and from Ordovician to Permian,marine(or transitional)deposits developed.The strata of Zhongba block can be clarified into Upper Sinian-Cambrian schist and Ordovician-Devonian metamorphic carbonate,Carboniferous-Permi

关 键 词：青藏高原中南部 前中生代 岩石地层 时代 

分 类 号：P534.1[天文地球—古生物学与地层学] P534.4[天文地球—地质学]