内蒙古苏尼特左旗北部中―上奥陶统巴彦呼舒组地层划分与沉积环境分析  

STRATIGRAPHIC SUBDIVISION AND DEPOSITIONAL ENVIRONMENT OF THE MIDDLE―UPPER ORDOVICIAN BAYANHUSHU FORMATION IN NORTHERN SONID ZUOQI OF INNER MONGOLIA

作　　者：白灵麒 金小赤[1] 刘建波[2] 鞠文信[3] 邱广东[3] 闵慧[3] BAI Ling-qi;JIN Xiao-chi;LIU Jian-bo;JU Wen-xin;QIU Guang-dong;MIN Hui(Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037;Department of Geology,Peking University,Beijing 100871;Inner Mongolia Institute of Geological Survey,Hohhot 010020)

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]北京大学地球与空间科学学院,北京100871 [3]内蒙古自治区地质调查院,内蒙古呼和浩特010020

出　　处：《地层学杂志》2019年第4期442-452,共11页Journal of Stratigraphy

基　　金：中国地质调查局天津地质调查中心“内蒙古1∶5万巴润茨呼勒、达来庙、乌兰呼都格、柴达木音浑迪幅区域地质矿产调查”项目(DD2016041-15)资助

摘　　要：巴彦呼舒组是一套分布于中蒙边界中东部的奥陶纪海相地层,研究程度有待提高。笔者釆用路线调查、剖面测量、薄片鉴定等手段,对内蒙古苏尼特左旗北部巴彦呼舒组的典型剖面进行了研究。巴彦呼舒组可划分出两个岩性段:一段主体为灰绿色、浅黄色、青灰色变质粉砂岩、粉砂质板岩、长石细砂岩,粉砂质板岩中夹灰岩透镜体,产笔石Haddingograptus oliveri、Jiangxigraptus alabamensis、Jiangxigraptus sextans、Proclimacograptus angustatus;二段主体为灰绿色、黄绿色、灰褐色变质长石细砂岩、岩屑长石细砂岩、粉砂岩和硅质粉砂岩。据化石组合特征与沉积构造分析,巴彦呼舒组的形成时代为中一晚奥陶世,沉积环境为近源的大陆斜坡环境。区域地层对比结果反映中一晚奥陶世研究区沉积环境稳定,具有大陆斜坡的环境特征。The Ordovician Bayanhushu Formation in the middle-east part of the China-Mongolia boundary area comprises moderately metamorphosed siliciclastic sediments.We describe here,based on field investigation and laboratory analysis,the lithological and paleontological contents of the formation and discuss the changes in its sedimentary environment.The Bayanhushu Formation is divided into 2 members.The lower Member 1 consists mainly of grayish green,yellowish and bluish gray metamorphosed siltstone,mudstone,and fine-grained arkose;some limestone lenses interbedded with silty slate.The upper Member 2 is composed of greyish green,yellowish green,and greyish brown metamorphosed fine-grained arkose,lithic arkose,siltstone,and siliceous siltstone.The graptolites Haddingograptus oliveri,Jiangxigraptus alabamensis,Jiangxigraptus sextans and Proclimacograptus angustatus have been discovered in Member 1 for the first time,suggesting a middle-upper Ordovician age for the formation.Sedimentary structures and petrographic properties of the formation indicate a continental slope environment.The stratigraphic correlation of the Bayanhushu Formation shows that in middle-late Ordovician sedimentary environment of the study area is stable,and has the characteristics of continental slope environment.

关 键 词：中一上奥陶统 巴彦呼舒组 地层划分 沉积环境 苏尼特左旗 内蒙古 

分 类 号：P534.42[天文地球—古生物学与地层学]