扬子台地西缘晚奥陶世凯迪早期地层划分对比与古地理  

EARLY KATIAN(LATE ORDOVICIAN)STRATIGRAPHY AND PALEOGEOGRAPHY OF THE WESTERN YANGTZE PLATFORM,SOUTH CHINA

作　　者：王光旭[1,2] 崔雨浓 张竹桐 吴荣昌 魏鑫[1,4] 梁艳 栾晓聪[1,2] 唐鹏 詹仁斌[1,2,3] WANG Guang Xu;CUI Yu Nong;ZHANG Zhu Tong;WU Rong Chang;WEI Xin;LIANG Yan;LUAN Xiao Cong;TANG Peng;ZHAN Ren Bin(State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,ChineseAcademyof Sciences,Nanjing210008;Center for Excellence in Life and Paleoenvironment,Chinese Academy of Sciences,Nanjing 210008;University of ChineseAcademyof Sciences,Beijing100049;The Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,School of Earth and Space Sciences,PekingUniversity,Beijing100871)

机构地区：[1]中国科学院南京地质古生物研究所,现代古生物学和地层学国家重点实验室,江苏南京210008 [2]中国科学院生物演化与环境卓越创新中心,江苏南京210008 [3]中国科学院大学,北京100049 [4]北京大学地球与空间科学学院,造山带与地壳演化教育部重点实验室,北京100871

出　　处：《地层学杂志》2022年第3期255-270,共16页Journal of Stratigraphy

基　　金：现代古生物学和地层学国家重点实验室(20191102、213123);中国科学院战略性先导科技专项(B类)(XDB26000000);中国科学院青年促进会(2020311)共同资助。

摘　　要：扬子台地西缘(今昆明—西昌—成都之间)晚奥陶世凯迪早期浅水相地层,过去多被视作“大箐组”(下部)或“宝塔组”,其划分对比一直存在争议,空间分布特征未得到充分揭示。综合研究新成果与前人的研究资料,本文提出研究区凯迪早期地层空间分布模式,即浅水相区可划分为以厚层白云岩为特征的近岸白云岩相带和以中至厚层生物扰动灰岩为特色的过渡灰岩相带,并由后者向台地内部过渡为以宝塔组为代表的远岸较深水灰岩相区。本文据此修订“大箐组”专指近岸相沉积,新建镇雄组代表过渡相沉积,认为二者均可对比于台地内部的宝塔组,时代为凯迪早期(或包含桑比末期)。在新的地层框架下,通过总结已有的剖面资料,本文还对研究区凯迪早期的古地理进行复原。Uncertainties remain as to stratigraphic subdivision,nomencalture and correlation of the lower Katian(Upper Ordovician)represented by the lower part of“the Taching Formation”in southwestern Sichuan and northeastern Yunnan provinces,palaeogeographically on the western Yangtze Platform of South China.Our recent investigations reveal a belt-like distribution of these rocks along the northwestern Dian-Qian-Gui and eastern Kang-Dian oldlands.The lithofacies belt can be subdivided into a near-shore belt with thick to massive dolomites,and a more offshore belt characterized by trace fossil-bearing limestones,which in turn laterally grade into distinctive,deeper-water meganodular limestones of the Pagoda Formation.Thus the Taching Formation is revised to include rocks of the former belt,and a new lithostratigraphic unit,the Zhenxiong Formation,is introduced for the strata of the transitional belt due to their unique lithology and wide distribution.Both the units can be correlated with the Pagoda Formation of early Katian age from the interior of the Upper Yangtze Platform.Within the revised stratigraphic framework,a refined early Katian paleogeographic map of the western Yangtze Platform is presented based on published and new data.

关 键 词：地层学 古地理 奥陶纪 凯迪早期 华南 

分 类 号：P534.42[天文地球—古生物学与地层学]