The Perturbation of the Guadalupian Marine Environment Triggered by Early-Stage Eruption of the Emeishan Large Igneous Province: Rare Earth Element and Sr-Nd Isotope Evidence from Zunyi Manganese Deposit, South China

Abstract

Pure marine chemical sediments are archives of geochemical proxies for the composition of seawater and may provide information about the ancient hydrosphere–atmosphere system. The early stage of the Emeishan large igneous province (ELIP) was characterized by the subaqueous eruption of mafic igneous rocks around the J. altudaensis zone of the Capitanian Stage that has been proposed to have contributed to the Guadalupian mass extinction. However, detailed mechanisms and the impact of the eruption on the Guadalupian marine environment have yet to be assessed. Here, to examine the Guadalupian marine environment, we studied major and trace element concentrations, particularly rare earth element and yttrium data, along with high-precision Sr-Nd isotope ratios, of three types of Mn ores (i.e., clastic, massive, and oolitic) and siliceous limestones from the Zunyi Mn deposit in South China formed following the early-stage eruption of the ELIP. Our results indicate that the clastic Mn ores contain notable detrital mafic aluminosilicates. In contrast, the massive and oolitic Mn ores and siliceous limestones preserved the pristine geochemical signatures of the Middle–Late Permian seawater characterized by distinctly low (87Sr/86Sr)i and high εNd(t) values. These data indicate a strong impact of the early-stage submarine eruptions of the ELIP on the marine environment in South China and worldwide, likely through intensive seawater–rock interaction.