扬子台地西缘晚奥陶世凯迪晚期地层划分对比与古地理  

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

作　　者：王光旭[1,2] 崔雨浓 魏鑫 吴荣昌 张竹桐[1,2,3] 王骞 詹仁斌 WANG Guang Xu;CUI Yu Nong;WEI Xin;WU Rong Chang;ZHANG Zhu Tong;WANG Qian;ZHAN Ren Bin(State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academyof Sciences,Nanjing 210008;Center for Excellence in Life and Paleoenvironment,Chinese Academy of Sciences,Nanjing 210008;University of Chinese Academy of Sciences,Beijing 100049;The Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,School of Earth and Space Sciences,Peking University,Beijing 100871)

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4期325-345,共21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);国家自然科学基金(42072007);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)晚奥陶世凯迪晚期地层的划分、对比与空间分布等方面仍存在诸多的不确定。本文综合新的研究成果和前人的资料,认为研究区这段地层可划归近岸白云岩相、近岸灰岩相、过渡混积相和远岸较深水相4个相带,并据此修订了前3个相带的地层框架,以实现与远岸较深水沉积(以临湘组和五峰组为代表)更高精度的对比。近岸白云岩相带以下部深灰色薄层硅质白云岩、上部薄至厚层白云岩夹含笔石碎屑岩为特色,以修订后的王家河坝组称之。近岸灰岩相带的该段地层下部为深灰色薄层硅质灰岩,上部为薄至厚层灰岩、白云质灰岩,常发育含笔石碎屑岩夹层,本文以修订后的铁足非克组称之。在过渡混积相带内,下部为深灰色薄层泥晶灰岩,常发育垂向管状遗迹化石,创名莲峰组;上部为灰岩与泥页岩不等厚互层,化石丰富,沿用大渡河组一名。同时,本文认为王家河坝组下段、铁足非克组下段和莲峰组均对比于临湘组;王家河坝组上段与五峰组可部分对比;铁足非克组上段和大渡河组均可与五峰组完全对比。在新的地层框架下,本文通过系统总结已有的资料,尝试对研究区凯迪晚期的古地理进行更高精度的复原。Uncertainties remain about the spatial distribution and stratigraphic subdivision and correlation of the upper Katian(Upper Ordovician)in southwestern Sichuan and northeastern Yunnan provinces,palaeogeographically on the western Yangtze Platform of South China.A compilation of new and published data indicates that these rocks fall into four lithofacies belts:The near-shore dolomite,near-shore limestone,mixed siliciclastic-caronate,and offshore shale-dominated.The Wangjiaheba and Tiezufeike formations are revised to represent the late Katian strata of near-shore dolomite and limestone facies,respectively.The lower part of the offshore succession is characterized by dark-grey,thin-bedded micrites,for which a new lithostratigraphic unit,the Lianfeng Formation,is proposed,and the upper part of the succession comprises alternating limestones and mudstones(or shales)widely known as Daduhe Formation.The Lianfeng and Daduhe formations grade laterally into nodular limestones of the Linhsing Formation,and black shales of the Wufeng Formation,respectively,and are as a whole dated as late Katian.Such a stratigraphic revision,together with a critical review of published data,allows a refined late Katian paleogeographic reconstruction of the western Yangtze Platform.

关 键 词：地层学 古地理 奥陶纪 凯迪晚期 华南 

分 类 号：P534.42[天文地球—古生物学与地层学]