Wenkun Qie

Carboniferous and Lower Permian sedimentological cycles and biotic events of South China

Abstract The sedimentary successions and four fossil groups, including rugose corals, brachiopods, fusulinaceans and conodonts, from the Carboniferous and Lower Permian of South China have been studied in order to reveal the sedimentary characteristics and evolutionary pattern of main biological groups in the East Tethyan region during the Late Palaeozoic Ice Age. The Lower Carboniferous lithology of South China is diverse, ranging from basinal and shelf carbonate rocks to coal measures and continental clastics, while the Upper Carboniferous and Lower Permian are composed mostly of shallow-marine carbonates. From uppermost Devonian to Lower Carboniferous, five major regression events are recognized at the topmost Devonian, middle and upper Tournaisian boundary, Tournasian–Viséan boundary, uppermost Viséan and the Mid-Carboniferous boundary in South China, separately. The Upper Carboniferous and Lower Permian shallow-water carbonate rocks consist of remarkable, high-frequency cyclothems. Moreover, another major sea-level fall is recognized and characterized by an extensive sedimentary hiatus at the Sakmarian–Artinskian boundary throughout South China. All of the sedimentary basins of South China were formed in extensional tectonic settings during this time; thus, multiple regressive events that occurred throughout South China should be primarily induced by glacio-eustatic drawdown. In addition, two biotic events characterized by a remarkable decline in the diversity of benthic biota and a turnover in the composition of fossil assemblages occurred, respectively, at the Mid-Carboniferous and Sakmarian–Artinskian boundaries, consistent with two major regressions, and were probably caused by the glaciations in Gondwana.

Pragian and lower Emsian (Lower Devonian) conodonts from Liujing, Guangxi, South China

LU, J.-F., QIE, W.-Q. & CHEN, X.-Q., July 2016. Pragian and lower Emsian (Lower Devonian) conodonts from Liujing, Guangxi, South China. Alcheringa 40, xxx–xxx. ISSN 0311-5518. Lower Devonian (Pragian and Emsian) conodonts are described from the Liujing section in Guangxi, South China, highlighting the phylogeny of early polygnathids and establishing the basis for faunal correlations with deposits throughout the world. Records of Eognathodus kuangi sp. nov. and E. nagaolingensis Xiong increase the biodiversity of the Pragian eognathodids in South China and represent intermediate stages and probably the latest eognathodids in the evolutionary succession from Eognathodus to Polygnathus. During this evolutionary succession, the degeneration of the sulcus (or the flattening of the upper platform surface) is the most important morphological change, especially in the eognathodid lineage. Polygnathus trilinearis, P. pireneae and P. sokolovi are recognized together for the first time in South China. The contemporaneous occurrences of the kitabiformis and sokoloviformis morphs of P. pireneae with P. sokolovi and their respective similarities to P. kitabicus and P. sokolovi suggest that the latter two species are phylogenetically linked with P. pireneae. Evidence from the Liujing section also favours Polygnathus probably having evolved from Eognathodus in a tropical or subtropical area. Jian-feng Lu* [lujfivan@sina.cn] and Xiu-qin Chen [xqchen@nigpas.ac.cn], Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, PR China; Wen-Kun Qie [wkqie@nigpas.ac.cn], Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, 39 East Beijing Road, Nanjing 210008, PR China. *Also affiliated with University of Chinese Academy of Sciences, Beijing 100049, PR China.

New Data on the Age of the Yukiang (Yujiang) Formation at Liujing, Guangxi, South China

The age of the Yukiang (Yujiang) Formation has been shrouded in controversy for more than 75 years. New investigation at the Liujing section, Hengxian County, Guangxi, has revealed a conodont sequence assignable to two Early Devonian conodont zonations: the Eognathodus kindlei?–Polygnathus pireneae Zone and the Polygnathus nothoperbonus Zone from oldest to youngest. The Gaoling and Mahuangling members of the Nahkaoling (Nagaoling) Formation and the overlying Xiayiling Member and lower part of the Shizhou Member of the Yukiang Formation are proven to belong to the Pragian Eognathodus kindlei?–Polygnathus pireneae Zone. The co-occurrence of Polygnathus pireneae and Pol. sokolovi in the lower part of the Shizhou Member demonstrates that this interval can be approximately correlated with the uppermost part of the Polygnathus pireneae Zone. However, precise level identification of the Pragian–Emsian Boundary (PEB) in the Liujing section remains dfficult due to the scarcity of suitable limestone samples for conodont analysis from the middle and upper parts of the Shizhou Member. The Daliancun and Liujing members of the Yukiang Formation and the lower part of the overlying Moding Formation are assigned to the Polygnathus nothoperbonus Zone with the nominal species of this biozone ranging from the bottom of the Daliancun Member to the lower part of the Moding Formation.

Carboniferous integrative stratigraphy and time scale of China

The Carboniferous period lasted about 60 Myr, from ~358.9 Ma to ~298.9 Ma. According to the International Commission on Stratigraphy, the Carboniferous System is subdivided into two subsystems, i.e., Mississippian and Pennsylvanian, including 6 series and 7 stages. The Global Stratotype Sections and Points (GSSPs) of three stages have been ratified, the Tournaisian, Visean, and Bashkirian stages. The GSSPs of the remaining four stages (i.e., the Serpukhovian, Moscovian, Kasimovian, and Gzhelian) have not been ratified so far. This paper outlines Carboniferous stratigraphic subdivision and correlation on the basis of detailed biostratigraphy mainly from South China, and summarizes the Carboniferous chronostratigraphic framework of China. High-resolution biostratigraphic study reveals 37 conodont zones, 24 foraminiferal (including fusulinid) zones, 13 ammonoid zones, 10 brachiopod zones, and 10 rugose coral zones in the Carboniferous of China. The biostratigraphic framework based on these biozones warrants the precise correlation of regional stratigraphy of China (including 2 subsystems, 4 series, and 8 stages) to that of the other regions globally. Meanwhile, the Carboniferous chemo-, sequence-, cyclo-, and event-stratigraphy of China have been intensively studied and can also be correlated worldwide. Future studies on the Carboniferous in China should focus on (1) the correlation between shallow- and deep-water facies and between marine and continental facies, (2) high-resolution astronomical cyclostratigraphy, and (3) paleoenvironment and paleoclimate analysis based on geochemical proxies such as strontium and oxygen isotopes, as well as stomatal indices of fossil plants.