A study on the genetic relations between Permian Longtan Formation coal series strata and Carlin-type gold deposits, southwestern Guizhou Province, China

摘要

A large number of the Carlin-type gold deposits occur in the Longtan Formation in southwestern Guizhou Province. The Longtan Formation contains abundant basalt, tuff and siliceous rocks. All rocks of the Longtan Formation are enriched in gold, which were deposited in a limited platform environment in the transition zone from marine to continental. The process of sedimentation was accompanied by the eruption of Emeishan basalt and hydrothermal deposition controlled by co-sedimentary submarine deep faults in the west, which led to the formation of a peculiar gold-bearing formation with coal series strata. This formation controlled the occurrence of the Carlin-type gold deposits in southwestern Guizhou Province. In response to the remobilization of the Emei mantle plume during the Yanshanian period, As, Au and other ore-forming materials were continuously extracted by deeply circulating waters from the Emeishan basalt and coal seams, thereafter forming ore-forming hydrothermal solutions. When these elements were transported in the coal seams, large amounts of As, Au and other elements were enriched in pyrite within the coal seams, thus forming high-As coal and Carlin-type gold deposits in the Longtan Formation coal series strata.