Underwater volcanic input revealed by iron and mercury isotopes in an alkaline lake during the Carboniferous‒Permian glaciation period in Junggar Basin, Northwest China

Numerous fresh samples of MY1 Well were collected at a spacing of 3–8 m according lithology changes for the analysis of the contents of total organic carbon (TOC, 80 samples) and organic carbon isotopes (δ13Corg, 80 samples), total sulfur (TS, 80 samples), major and trace elements (80 samples), and mercury (Hg, 80 samples) as well as iron speciation (70 samples). These analyses were conducted at China University of Geosciences (Wuhan). A subset of dissolved whole-rock iron isotopes (δ56FeT, 40 samples) and mercury isotopes (δ202Hg and Δ199Hg, 23 samples) were analysed for degerming the pathways of different volcanic eruptions. These analyses were conducted at the Institute of Geochemistry, Chinese Academy of Geological Sciences, and Tianjin University, China, respectively. All the rocks were crushed to less than 200 mesh for analysis.