Preliminary Study on the Assessment of Mercury Concentration Anomalies Since the Phanerozoic and the Coupling Relationship Between Carbon and Mercury

<p indent="0mm"> Biological mass extinctions have occurred repeatedly throughout Earth′s long history, especially since the Phanerozoic, when at least five global mass extinctions have occurred, and mercury (Hg) has attracted much attention in the geologic record as a key clue linking these events to the eruption of large igneous provinces. However, previous studies have tended to focus on Hg concentration anomalies over specific periods of time with major events occurred, and have lacked a holistic understanding of the evolution of Hg over large scales of geologic history. In addition, total organic carbon (TOC) as the main host for mercury in sediments, there are many unknowns about the co-evolutionary relationship between TOC and Hg. Therefore, this study is based on the Hg and carbon records in The Sedimentary Geochemistry and Paleoenvironments Project (SGP) database and data for the Big Five mass extinctions in recent years to solve the above problems. By observing the changes of elemental concentration in each period, this study found that Hg and TOC had similar trends during the Phanerozoic period, and the four highest Hg peaks recorded in the SGP database were found to be located at 508, 401, 298, and <sc>111 Ma;</sc> And a positive correlation between Hg and TOC concentrations in sediments was found by Spearman′s rho correlation coefficient and regression analysis. Comparing previous interpretations of Hg concentration anomalies in the geologic record and studies of the relationship between Hg and TOC in sediments, we explored possible factors contributing to Hg anomalies in sediments, and we suggest that: (1) The sources of Hg in the environment are complex and varied, and anomalous accumulations of Hg in sedimentary rocks do not always originate from the LIP, and a combination of possible factors needs to be considered when interpreting Hg concentration anomalies; (2) The relationship between Hg and TOC concentrations in different lithologies shows significant differences. Data on Hg and TOC concentrations in carbonatites and siliciclastic clastic rocks work best with zonal fitting, suggesting that Hg and TOC concentrations in sediments may be coupled differently in different depositional environments. Hg and TOC concentrations in carbonatites and siliciclastic rocks may be linear in reducing environments and logarithmic in normal marine environments, and Hg and TOC contents in siliciclastic rocks may be linear or logarithmic in high primary productivity environments.