Intense continental weathering during the early Ediacaran; in the aftermath of the Marinoan snowball Earth

The Ediacaran period witnessed one of the most significant episodes of biological evolution in Earth's history. To reconstruct the environmental changes during this period, researchers have employed multi-geochemical proxies from Ediacaran strata. Continental weathering exerts a major influence on seawater composition and the evolution of life, and its flux can be estimated using the 87 Sr/ 86 Sr ratio of carbonate rocks. The secular variation of Ediacaran marine 87 Sr/ 86 Sr composition has been primarily reconstructed from Ediacaran strata in South China. However, because existing 87 Sr/ 86 Sr data are derived from tidal flat to shelf margin settings, clarifying the 87 Sr/ 86 Sr ratios in more distal settings is essential for comprehensively tracking the 87 Sr/ 86 Sr composition of the open ocean. We conducted on-land drilling to collect Ediacaran sedimentary rocks from the Tianping and Siduping sections, both located in slope settings. SEM-EDS observations revealed that the carbonate rocks at these sections experienced dolomitization, clay mineral formation, and silicification during diagenesis. Clay mineral-free carbonate rocks exhibit positive La and Y anomalies, indicating deposition in an open marine environment. 87 Sr/ 86 Sr values in the basal Doushantuo Formation at the Tianping section decreased from approximately 0.709 to approximately 0.708. This highly radiogenic value following the Marinoan glaciation is a novel finding of this study and suggests an elevated continental weathering influx post-Marinoan glaciation. 87 Sr/ 86 Sr profiles at the Siduping section demonstrate that high 87 Sr/ 86 Sr ratios around the Shuram excursion are common features of carbonate rocks deposited in various settings at this time. Consequently, this study confirms that continental weathering was elevated at approximately 635 Ma, 580 Ma, and 560 Ma. These timings coincide with three intervals of Mo enrichment in euxinic shales. This supports the hypothesis that globally elevated rates of continental weathering were closely linked to ocean oxygenation events during the Ediacaran. • We obtained Ediacaran sediments at the Siduping and Tianping sections by drilling. • We newly presented the stratigraphic profiles of 87 Sr/ 86 Sr ratio at slope facies. • Continental weathering rate after Marinoan snowball Earth was elevated. • High 87 Sr/ 86 Sr ratios during the Shuram excursion were common in various settings.