青海南部早二叠世火山-沉积背景的岩石地层序列  

Early Permian (Cisuralian) Lithostratigraphical Succession in Volcanic-Sedimentary Setting from Southern Qinghai

作　　者：牛志军[1] 段其发[1] 王建雄[1] 何龙清[1] 白云山[1] 

机构地区：[1]中国地质调查局宜昌地质调查中心,湖北宜昌443003

出　　处：《地球科学（中国地质大学学报）》2010年第1期11-21,共11页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金(No.40972006);国土资源大调查(Nos.1212010911035;200213000003);2008年度国土资源部"百名优秀青年科技人才"资助

摘　　要：研究区位于青海南部长江源区,大地构造上属东特提斯构造域,为金沙江结合带与澜沧江结合带间昌都地块的一部分.青海南部二叠系沉积类型复杂,多呈断块(片)状出露,尤其是受火山事件影响的下二叠统.关于下二叠统(乌拉尔统)的对比及地层划分目前仍存在较多争议,认识的不同点主要集中于火山岩的层序归属、地质时代、区域对比等.以实测剖面为基础,系统调查岩石地层的岩性组合、沉积环境等,通过着重于各地层单位(尤其是火山岩系)的生物群研究,重新厘定火山-沉积背景下的岩石地层序列.■类动物群的研究表明诺日巴尕日保组和九十道班组在青海南部地区具穿时性.地层序列的建立表明青海南部早二叠世早期为较稳定的浅灰色中厚层状碳酸盐岩.罗甸期强烈的火山喷发,形成了特殊火山-沉积地貌,对沉积古地理格局形成明显的制约,沉积相变快,可划分为4种沉积类型,形成同期异相的诺日巴尕日保组和尕笛考组.自祥播期之后,主要为一套厚层状生物屑灰岩(九十道班组),在青海南部分布较广,代表火山活动暂时停止后的台地相沉积,罗甸期复杂的古地理格局,至此则构成相对统一的较稳定的浅水碳酸盐岩台地.The studied area is situated at the origin of the Yangtze River in the Tanggula Mountain of southern Qinghai, which was a part of the Qamdo Block of the East Tethyan tectonic domain during the Late Palaeozoic and is bounded by the Jinshajiang suture to the north and the Lantsang-Lungmo Co suture to the south. The Permian strata is widespread in the area with various sedimentary facies, and separated by numerous and complicated faults, especially Lower Permian influenced by volcanic activity. As a result of complex regional tectonics and depositional types, there has been much controversy over the Lower Permian （Cisuralian） classification and correlation, which mainly involves issues including succession, age and regional correlation of volcanic rocks. According to the study of lithographic association of sedimentary environment and fauna of lithos tratigraphieal unit （especially volcanic rocks）, the sequences in volcanic-sedimentary setting are refined in this paper. The Jiushidaoban and Nuoribagaribao formations are diachronous in southern Qinghai according to the fusulinid data. The Permian succession indicates that the Zharigen Formation composed mostly of carbonate rocks occupied the main part of the southern Qinghai, belonging to a stable platform during early stage of the Early Permian. The Luodianian strong volcanic eruption led to a depositional differentiation, forming the Qadikao Formation and contemporaneous Nuoribaribao Formation. As a result of volcanic product and sedimentary process, a complex volcanic-sedimentary landform occurred on sea floor and controlled the distribution of sedimentary facies. Four sedimentary types were recognized based on detailed field mapping and analysis of lithographic association. Jiushidaoban Formation mainly characterized by carbonate rock is widespread in southern Qinghai, which is a representative of platform facies during the intermission period between volcanic activities, which shows that the complex palaeogeographic structure of alternate volcano island

关 键 词：二叠系 筵类 岩石地层 地层学 青海 

分 类 号：P534[天文地球—古生物学与地层学] P539[天文地球—地质学]