Influence of the Late Ordovician‐Early Silurian Paleoenvironment and Related Geological Processes on the Organic Matter Accumulation and Carbon Isotope Excursion

作者：Pengyuan Zhang, Yongli Wang, Zhifu Wei, Gen Wang, Ting Zhang, Wei He, Xueyun Ma, He Ma, Jingyi Wei, Chenxi Zhu · 发表于：Paleoceanography and Paleoclimatology · 年份：2023 · DOI：10.1029/2023pa004628 · 被引用次数：11 · 研究领域：Paleontology and Stratigraphy of Fossils、Geochemistry and Elemental Analysis、Hydrocarbon exploration and reservoir analysis

Abstract Although previous studies have shown that the paleoenvironment and geological processes contributed to the organic matter accumulation (OMA) and carbon isotope excursions (CIEs) during the late Ordovician–early Silurian, the dominated controlling factor for the OMA and the origins of CIEs still remains unclear due to complex interaction between various paleoenvironmental factors and geological processes. Therefore, based on the elemental geochemistry of the Wufeng–Longmaxi Formation shales in the upper Yangtze Platform, we analyzed the late Ordovician–early Silurian paleoenvironment and related geological processes, and further explored the origin of the OMA and CIEs. As a result, the Wufeng–Longmaxi Formation shale was divided into four stages. During Stage 1 (late Katian, ∼447.62–444.50 Ma), local tectonic and volcanic activities controlled the paleoproductivity and redox conditions, facilitating the OMA. By contrast, the productivity of the surface water and the anoxic bottom water were mainly controlled by the global climate after the Hirnantian glaciation, which contributed to the OMA during Stage 2 (early Rhuddanian, ∼444.50–441.00 Ma). The decreasing sea level and rapid uplifting of Xuefeng and Qianzhong Uplifts resulted in the organic matter depletion during Stages 3 (late Rhuddanian, ∼441.00–440.80 Ma) and 4 (Aeronian, ∼440.80–439.21 Ma). Besides, the release of 12 C–enriched carbon reservoirs triggered by volcanic activities and 13 C–enrichment caused by th...