Enrichment of Multiple Elements and Depositional Environment of Seleniumrich Deposits in Yutangba, Western Hubei

Key words: 
• Yutangba

Abstract: Total organic carbon (TOC), and total sulfur (TS), total iron (TFe) contents were analyzed in the siliceous rocks (bedded chert) and shales sampled from the selenium deposit of Yutangba, western Hubei , based on which the mechanism of enrichment of multiple elements and depositional environments (i.e., redox conditions) are documented. The enrichmental factors of V，Se，Cd，Sb are larger than 10; those of Co，Ni，Cu，Zn，Ge，As，Tl，U are in the range between 1 and 10. The S/Fe ratios are generally greater than 1.15, suggesting that surplus sulfur may have occurred, which may have accelerated the precipitation of organicbound sulfur and some chalcophile elements. The triangular diagram of TOCTSTFe, the ratios of V/(V + Ni), and the relationship between some elements and TOC suggest that the seleniumrich black rocks (black shales and bedded chert) were deposited in anoxic and euxinic environments. In addition, some geochemical parameters, such as U/Th ratios,ZrCr, PY abundances in the sediments, suggest that hydrothermal processes might have occurred during the deposition. Multiple sources of trace elements, i.e., marine, hydrothermal inputs and Emeishan basalts, were likely responsible for deposition of the seleniumrich deposits at Yutangba, western Hubei.