The Emeishan large igneous province eruption triggered coastal perturbations and the Capitanian mass extinction: Insights from mercury in Permian bauxite beds

The Capitanian mass extinction occurring at the mid-Capitanian to the Guadalupian-Lopingian boundary (GLB; ca. 262-257 Ma) was temporally coincident with the eruption of the Emeishan large igneous province (LIP). Recent observation of Hg anomalies at the GLB at shelf and slope/basinal settings demonstrated a possible causal link between the Capitanian extinction and the Emeishan LIP eruption. However, Hg records of the GLB at coastal settings remain uninvestigated, limiting our knowledge of global impact of the Emeishan LIP and its role in the Capitanian mass extinction. Here we report new datasets of Hg concentrations, Hg isotopes and organic carbon isotopes in two coastal shallow-water sections in the Guangxi region, SW China. Elevated Hg/TOC ratios (up to 3330 and 221 ppb/wt%, respectively) and near-zero to positive Delta 199Hg values (-0.04%o to +0.26%o) were observed across the GLB in the two sections, indicative of extensive volcanic Hg input to the ocean via wet Hg(II) deposition. A negative delta 13Corg excursion (2.5%o) coincides with widespread marine anoxia, peak Emeishan LIP magmatism, Hg/TOC anomalies, sea-level rise, and the Capitanian mass extinction. The temporal link between these phenomena suggests that the Emeishan LIP was a key driver of the climate/ocean dynamics, global eco-systems, and the formation of bauxite beds during the GLB.

Automated summary

This study reports new datasets of Hg concentrations, Hg isotopes, and organic carbon isotopes in two coastal shallow-water sections in the Guangxi region, SW China. The results show elevated Hg/TOC ratios and near-zero to positive Δ199Hg values across the Capitanian extinction, indicating extensive volcanic Hg input to the ocean via wet deposition. The negative δ13Corg excursion coincides with marine anoxia, peak Emeishan LIP magmatism, Hg/TOC anomalies, sea-level rise, and the Capitanian mass extinction.