Geochemical characteristics of the Upper Devonian Shetianqiao Formation in the Shaoyang sag of Xiangzhong depression from Middle Yangtze area, South China: Implications for the depositional environment and organic matter enrichment

The formation and preservation conditions of the organic matter (OM) in the Upper Devonian Shetianqiao Formation were investigated to assess the mechanism of the OM enrichment in the shale in the Shaoyang sag. The total organic carbon (TOC) contents of the shale range from 0.2% to 4.4%. The shale can be divided into three intervals. The terrestrial input during Interval 2, as indicated by the Al2O3 and Ti proxies, was relatively small. The...