Conodont evolution and stratotype sign of carboniferous Tournaisian-Visean boundary in South China

A stratotype section, boundary point and conodont sign have been recommended for GSSP of the Tournaisian-Visean boundary, based on studies of sectional sedimentology, conodont facies and phylogeneses in South China. Two areas representing margin and inner of the Yangtzi Plate and three sections of different facies were chosen, i.e. the Longdianshan section of the platform facies in Liuzhou of Guangxi, the Yudong section of the ramp facies in Shidian of Yunnan and the Pengchong section of the basin facies in Liuzhou of Guangxi. Stratigraphic frameworks of two areas were set up by systematical studies of carbonate facies and cycles. Conodont facies-distribution and paleoecologic conditions were researched on statistics of fossil variation and richness, and a kind of planktonic conodont, gnathodids that were widespread, is chosen to select the sign-fossil from it. Seven conodont pedigrees were supplemented or erected by studies of statistics and transitional forms. Conodont evolution in the Early Carboniferous could be divided into three stages, i.e. the Siphonodella stage, the Gnathodus typicus stage and the Gnathodus bilineatus stage. The transform-surface between the later two stages could be put as the Tournaisian-Visean boundary. Finally, this paper proposes that the Pengchong section can be the stratotype candidate of the Tournaisian-Visean boundary, the boundary point be put at the bottom of bed 58 and the stratotype sign of conodont be the first occurrence of Gnathodus praebilineatus of the Gnathodus semiglaber branch.

作 者： TIAN Shugang Michel Coen   作者单位： TIAN Shugang(Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China)

Michel Coen(Louvian University of Belgium, B-1348 Louvian-la-Neuve, Belgium) 

刊 名： 中国科学D辑（英文版）  SCI 英文刊名： SCIENCE IN CHINA (EARTH SCIENCES)  年，卷(期)： 2005 48(12)  分类号： P5  关键词： Tournaisian-Visean boundary   global stratotype   conodont evolution