Physical properties of the triassic host strata and their relations with gold mineralization in Youjiang Rift, South China

Micro-fine disseminated gold deposits are hosted in the Triassic Baipeng Formation (argillaceous siltstone and arenaceous mudstone) in the Youjiang Rift, South China. Physical properties (grain size, specific surface, porosity and permeability) of the host rocks are studied with respect to ore-fluid circulation, water-rock reaction and the effective volume from which ore-components could be extracted. On this basis, it is considered that the ore-fluid and ore-metals were extracted mainly from the strata and hydrothermal solutions, tending to move towards low-energy sites, depositing their gold in fault zones at the margins of the basin and in the circle fracture systems around underwater uplifts. The gold deposits resulted from the deep-circulation of hydrothermal solutions, probably aided by multi-stage superimposition. The quantities of ore-fluid necessary to form the deposits were estimated. This project was jointly granted by the National Natural Science Foundation of China and the Doctoral Program Funds of National Education Committee of China.