西藏北部班戈地层分区下白垩统郎山组、康曲组和余穷组地层层序研究  

STRATIGRAPHIC SUCCESSION OF THE LOWER CRETACEOUS LANGSHAN,KANGQI AND YUQIONG FORMATIONS IN THE BAINGOIN DISTRICT, NORTHERN TIBET

作　　者：曲永贵 刘贵忠 郑春子 王永胜 张树岐 

机构地区：[1]吉林地质调查院,吉林长春130061

出　　处：《地层学杂志》2003年第3期220-226,共7页Journal of Stratigraphy

基　　金：地调项目:<多巴区幅> 1/ 2 5万国土资源大调查项目(2 0 0 0 13 0 0 0 0 92 5 1)

摘　　要：在西藏自治区北部区域地质调查过程中 ,在班戈地层分区的下白垩统郎山组之上发现一套厚约 180 0 m的滨海—浅海相碳酸盐岩、陆源细碎屑岩岩石组合 ,该套组合不属于郎山组定义之内 ,且出露良好、层序稳定、标志清楚、厚度巨大、化石丰富 ,并具有很强的可填图性。因此 ,我们将整合于郎山组之上 ,岩性以杂色微—薄层状钙质泥岩、钙质 (粉 )砂岩与泥质生物灰岩的韵律产出为特征 ,产圆笠虫、腹足类、双壳类等化石的地层命名为康曲组 ;将整合于康曲组之上 ,下部以灰—深灰色中薄层状泥质生物灰岩、圆笠虫泥晶灰岩、钙质泥岩等韵律出现为特征 ,上部以灰色中—厚层状含硅质结核圆笠虫泥晶灰岩、圆笠虫泥晶灰岩夹灰绿色薄层状钙质砂岩为特征 ,富含圆笠虫、腕足类、腹足类、双壳类及海胆等化石的地层定名为余穷组。The new stratigraphic units, the Lower Cretaceous Kangqu, Yuqiong Formations, are established by the authors from the Baingoin District, northern Tibet. The Langshan Formation is represented by dark grey limestone with orbitolinids. The fragmentary rocks with thin bedded limestone are the predominant rock type in the Kangqu Formation. The Yuqiong Formation is regarded as alternating beds of marlite,argillaceous limestone, limestone with orbitolinids, calcareous sandstone, calcareous shale. The new stratigraphic sequence of the upper part of the Lower Cretaceous in the Baingoin District, northern Tibet is given below in descending order: Yuqiong Formation (the top is not exposed)>1266.07m Upper part: grey medium to thick bedded silicate nodular micritic limestone,micritic limestone with greyish green thin bedded calcareous sandstone intercalated, containing orbitolinids,brachiopods, gastropods, bivalves, and echinoids Lower part: grey dark grey thin to medium bedded argillaceous organic limestone, micritic limestone and mudstone,yielding orbitolinids,bivalves, and calcareous algae. conformity Kangqu Formation475.86 m variegated thin bedded calcareous mudstone, calcareous silty sandstone and argillaceous organic limestone, containing orbitolinids,gastropods, and bivalves conformity Langshan Formation (Albian)796.31 m limestones containing orbitolinids, brachiopods,and bivalves

关 键 词：西藏 班戈 地层 下白垩统 郎山组 康曲组 余穷组 白垩系 

分 类 号：P534.53[天文地球—古生物学与地层学]