1. Introduction Latest Ordovician to earliest Silurian strata and fossils, mainly the strata of the Wufeng Formation, Kuanyinchiao Formation, and the lowest Lungmachi Formation, are widely distributed on the Yangtze plat- form (Fig. 1). Graptolites and brachiopods occur commonly in these rocks throughout the region. Thirty-seven sections from the Yangtze region (Locs 1–4, 6–38 in Fig. 1) have been measured and collected by the authors and other Chinese colleagues in the past 30 years (Mu et al. 1993). One section at Bajiaokou, Ziyang (Loc. 5) was recorded from the South Qinling mobile belt, along the north slope of the Yangtze platform. Five (Locs 39–43) are from the Xiangwan basin, the successor of the Zhujiang pre- Ashgill basin. Localities 39 to 41, along the former Jiangnan belt, occur along the slope of the Xiangwan basin. Cathaysian Land experienced uplift beginning in the Ashgill and merged with Dianqian Land (Central Guizhou Land). Moreover, Cathaysian Land became more prominent northwestwards during the late Ashgill. Thus, the Yangtze platform was sur- rounded by Cathaysian Land, Dianqian Land and the Chengdu uplift, forming a semi-enclosed bay that opened northwards during late Ashgill time (Chen, Xiao & Chen, 1987). Lee & Chao (1924) and Grabau (1924) were the first to collect and identify the latest Ordovician to earliest Silurian fossils when they erected the Lungma Shale from the Yangtze Gorges. Sun (1931) identified the graptolites collected by Hsieh and Liu from Yuyangguan, Wufeng County, southern Hubei, as Ashgill in age and then named the strata the Wufeng Formation. Sun (1933) subsequently described the Wufeng graptolites. Despite this work, the Ashgill age of the Wufeng Formation was still not commonly accepted by palaeontologists in China. It was Mu (1954), when he re-studied the Wufeng graptolite fauna and correlated the Wufeng Formation with other related strata within South China, who firmly estab- lished the age of the formation, which was then used as Geol. Mag. 137 (6), 2000, pp. 623–650. Printed in the United Kingdom © 2000 Cambridge University Press 623 Late Ordovician to earliest Silurian graptolite and brachiopod biozonation from the Yangtze region, South China, with a global correlation CHEN XU*§, RONG JIAYU*, CHARLES E. MITCHELL†, DAVID A. T. HARPER‡, FAN JUNXUAN*, ZHAN RENBIN*, ZHANG YUANDONG*, LI RONGYU* & WANG YI* *Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, the People’s Republic of China †Department of Geology, State University of New York at Buffalo, Buffalo, NY 14260, USA ‡Geological Museum, University of Copenhagen, Oster-Volgade 5-7, DK-1350, Copenhagen, Denmark (Received 2 March 2000; accepted 15 August 2000) Abstract – Late Ordovician to earliest Silurian is an important geological period marked by large geo- logical and biological events. However, the strata and fossils of this interval are not complete in many parts of the world. Based on studies of 43 sites in South China, in particular the continuous sections on the Yangtze platform, we recognize a complete succession including seven graptolite zones and two shelly faunas. In ascending order, the graptolite zones are the Dicellograptus complanatus, Dicellograptus complexus, Paraorthograptus pacificus (including Lower Subzone, Tangyagraptus typi- cus Subzone and Diceratograptus mirus Subzone), Normalograptus extraordinarius–Normalograptus ojsuensis, Normalograptus persculptus, Akidograptus ascensus and Parakidograptus acuminatus zones. The shelly faunas are the Foliomena–Nankinolithus and Hirnantia faunas, which may be correlated with D. complanatus Zone and N. extraordinarius–N. ojsuensis to part of N. persculptus zones respec- tively.The biozonation through this interval from the Yangtze region can be correlated with that of other parts of the world such as Dob’s Linn in Scotland, Spain and Portugal, Thuringia–Saxonia– Bavaria, Bohemia, Poland, Kazakhstan, Kolyma, Malaya Peninsula, Yukon, Canadian Arctic Islands, Nevada, Argentina, Niger and Victoria, Australia. The Hirnantian Substage, which has been pro- posed by us recently, includes the N. extraordinarius–N. ojsuensis Zone, Hirnantia fauna and N. per- sculptus Zone. The base of the Hirnantian Substage is marked by the First Appearance Data (FADs) of N. extraordinarius and N. ojsuensis, which have been determined to be synchronous on a global scale. §Author for correspondence: xuchen@jlonline.com