Palynology and stratigraphy of the thick evaporate-bearing Shashi Formation in Jiangling Depression, Jianghan Basin of South China, and its paleoclimate change

Abstract

In the greater inland Jianghan Basin of South China, three salt depressions are lacking accurate geological times, of which Jiangling Depression is the largest. Evaporites are important records of paleoclimate, however, the geological ages of evaporates are very difficult to be determined because often evaporates have scare macrofossils and microfossils. Nonmarine Cretaceous to Tertiary halite deposits interbedded with mudstones are widely distributed in China. Paleocene-Eocene Thermal Maximum had very high temperatures and attracted strong interests of geologists because these times can be compared with future climate change because of global warming. However, previous studies focused on marine sediments found that during the Paleocene-Early Eocene, massive evaporate deposits formed in Jiangling depression of the Jianghan Basin. In this paper, the authors show that the Shashi Formation halite deposits formed in the Paleocene according to palynology. Most of these palynology fossils are arid types, so the massive evaporites in the Jiangling depression could be closely related to the hot Paleocene climate. High temperatures during the Paleocene contributed to the formation of the massive evaporates in the Jiangling Depression, until sylvite was the result.