Effects of astronomical orbital cycle and volcanic activity on organic carbon accumulation during Late Ordovician-Early Silurian in the Upper Yangtze area, South China

ZHANG Xi,ZHANG Tingshan,ZHAO Xiaoming,ZHU Haihua,MIHAI Emilian Popa,CHEN Lei,YONG Jinjie,XIAO Qiang,LI Hongjiao

Fig. 1. Paleogeography in the Yangtze region and the characteristics of the Jienietuo outcrop section during Late Ordovician-Early Silurian. (a) Lithofacies distribution and section location; (b) Paleogeography of the study area; (c) Lithologic column of Jienietuo section; (d) Cyclostratigraphic characteristic of outcrop; (e) Bentonite in black shale (volcanic ash).