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The Early Cambrian Late Stage 2 to Stage 3 (ca. 526–514 Ma) was characterized by the peak of the Cambrian Explosion and a large-scale global transgression that resulted in the deposition of organic-rich black shales, which have important implications for Earth-system science and petroleum/economic geology. However, there are many uncertainties regarding the spatiotemporal evolution of structural model, and driving mechanisms of the paleo-oceanic environment during this period, requiring more examples and research constraints. To fill the knowledge gap, high-resolution elemental, carbon isotope, and biogeochemical data were obtained from two continuous drill cores, along with redox-sensitive proxy data from additional 21 cores/sections of different sedimentary facies in the Yangtze Platform, South China, provide a comprehensive and detailed spatiotemporal window into this issue. It demonstrates that the dynamic evolution process of redox conditions varied between shallow- and deep-water regions, and temporal variations in chemical weathering intensity and spatiotemporal differences in upwelling currents controlled the redox state of the ocean, which was closely related to the relative contents of organic carbon (TOC), SO 4 2−, and Fe2+. The mechanisms that controlled the scale of sulfidic wedges differed among different regions and stages. During intervals I (Late Stage 2) and II (Early–Middle Stage 3), shallow and deep waters were controlled mainly by TOC and SO 4 2− contents, respectively. Deep waters during interval III (Late Stage 3) were controlled mainly by TOC contents. The spatiotemporal heterogeneity of the Early Cambrian paleo-ocean redox state partly controlled the spatiotemporal distribution of the fossil record. Primary productivity was the main controlling factor on the spatiotemporal variations in hydrocarbon source rock quality, followed by the organic matter preservation conditions. This study highlights the Earth-system science research on the deep-time ocean environment and its resource effects. [ABSTRACT FROM AUTHOR]

The Neoproterozoic provides an important record of glacial–postglacial paleoenvironments, organic carbon cycling, and hydrocarbon accumulation. Here, to better understand the environmental, sedimentary, and petroleum geological potential of the Neoproterozoic, we summarize and review research on paleoenvironment and hydrocarbon prospectivity during the era for regions worldwide and also present a case study of the Marinoan postglacial Ediacaran Doushantuo Formation in the Sichuan Basin, upper Yangtze region, China. Sediments that were deposited during the Neoproterozoic postglaciations generally have hydrocarbon-generating potential. In some places, the sediments have reached stages of burial and thermal evolution appropriate for hydrocarbon generation, with some sites having been exploited for commercial production. In the Sichuan Basin, the distribution and thickness of Doushantuo Formation sediments were controlled by glacially eroded topography and/or extension-related subsidence. Abundant organic matter was produced through paleo-productivity (Ba/Al and Cu/Al proxies can reach up to 181.08 and 8.94, respectively) and anoxia (U-EF and Mo-EF proxies can reach up to 5.45 and 14.00, respectively) governed by marine transgression. In South China, many depocenters of the Doushantuo Formation sediments have a strip-shaped geometry in the plane and are expected to be prospective for oil and gas. The reported findings can be used as a reference for further studies of glacial and postglacial deposits with organic matter accumulation of the Neoproterozoic and other periods. [ABSTRACT FROM AUTHOR]