关键词: 硫同位素, 早-中奥陶世, 海水氧化还原, 奥陶纪生物大辐射事件, 华南

Abstract:

To improve understanding of the environmental influential and controlling factors of the Great Ordovician Biodiversification Event (GOBE), total organic carbon content (TOC), total sulfur content (TS), and sulfur isotope of pyrite (δ³⁴S_py) of black shale of the Jiangjunling section, in southern Anhui Province, China are analyzed. TOC and TS show positive correlation, indicating non-euxinic environment. δ³⁴S_py exhibits obvious decrease in Floian and more oscillation in the Middle Ordovician. Combined with global sulfur isotope of carbonate-associated sulfate (δ³⁴S_CAS) and δ³⁴S_py data from previous researches, a marine oxygenation event is suggested by decreasing pyrite burial and increasing sulfur isotopic fractionation during the latest Tremadocian to middle Floian, which might boost GOBE. During the late Floian to Darriwilian, δ³⁴S_CAS from different areas decreases in succession, while δ³⁴S_py is characterized by large oscillation, which is contributed to low sulfate concentration and sulfide reoxidation in the ocean.

Key words: sulfur isotope, Early to Middle Ordovician, redox condition of seawater, the Great Ordovician Biodiversification Event, South China