Supergene ore and hypogene sub-economic gold mineralization at Shewushan, Hubei, central China

摘要

The Shewushan gold deposit is a tectonic mélange-hosted, disseminated, supergene-enriched deposit. The mineralization consists of sub-economic hypogene protore and economic supergene ore. The hypogene mineralization, hosted by tectonic mélange and crushed clay-rich limestone, is typified by gold-bearing pyrite and sub-micrometre native gold particles. The supergene mineralization is in the form of a layer located in the lower portion of the weathered mantle near the water-table. The hypogene mineralization was structurally controlled and was formed in close association with well-developed faults and fractures, mainly on the crest of a reverse anticline. The mineralization is largely confined to areas of the stratigraphy that consist of clay-rich limestone and carbonate-rich mudstone. Both hypogene and supergene gold mineralization are closely associated with As and Sb, which indicates that As and Sb thiosulphate may have played an important role in gold dissolution and reprecipitation.