Anomalous mercury enrichment in Early Cambrian black shales of South China: Mercury isotopes indicate a seawater source

Extremely elevated Hg levels up to the μg g− 1 range were found in sulfide-rich black shale and phosphorite in the lowermost part of the Early Cambrian black shale sequences on the Yangtze Platform in South China. In this study, mercury isotopes were used to help resolve the origin of this anomalous Hg enrichment. Mass independent fractionation signatures of Hg isotopes with positive Δ199Hg values of 0.13 to 0.24‰ and positive Δ200Hg values of...