Multi-Proxies Analysis of Organic Matter Accumulation of the Late Ordovician–Early Silurian Black Shale in the Lower Yangtze Region, South China

The evolutional process of palaeoceanic environment and its effect on the accumulation organic matter during Ordovician–Silurian transition in Lower Yangtze region has been overlooked compared to that Upper South China, although their paleogeographic settings were expected be discrepant. This paper documents marine depositional environment, paleoclimate, sediment supply changes, discusses roles controlling enrichment sedimentary rocks within region, using latest geochemical data continuous drilling core. stratigraphic framework is composed two third-order sequences, each which can subdivided into a lower TST (transgressive systems tract) an upper RST (regressive tract). TST1 represented evident stage was marked by ending underlying carbonate sediments initiation terrigenous clastic-dominated sediments. Geochemical proxies indicate relatively low productivity, dysoxic water column condition, high flux collectively resulted inadequate hosted deposits TST1. During period RST1, global sea level declined due Hirnantian glaciation age. icehouse also caused decrease overall river and, thus, clastic supply. strengthened upwelling occurred sea. boosted algae explosion through delivery abundant nutrients, not only enhanced paleoproductivity but led anoxic oxygen consumption. Such paleoproductivity, deposition organic-rich shale. rose TST2 ice large depth associated with volcanic eruptions are main factors this stage. RTS2, increase accommodation space dilution deposits, primary constraint accumulation.