Depth of ore deposit formation and prognosis of deep-seated ore deposits.

Abstract: This paper deals with the depths of mineralization and vertical range of metal precipitation of different endogenic ore deposits. The lower limit of the depth of hydrothermal mineralization may reach 10-12 km below the surface. The depth ranges of different types of deposit are closely related to the characteristics of particular geological structure and magmatism at the time of mineralization, and the ore deposits show a very large variation space. The depth of metal deposit formation is constrained by the depth of emplacement of parent ore magmas, while the depth of magmatic emplacement is in turn related to such factors as the quantity of volatile components in parent magmas, fluid separation time and partitioning coefficients between minerals and melts and between hydrothermal fluids and melts. Thus, we may explain the differences in mineralization depths of porphyry Cu (-Mo) deposits, porphyry Mo (-Cu) deposits and porphyry W deposits. The depths of mineralization are also related to geothermal gradients and permeability of porous rocks. Because the solubility of volatiles such as CO2 is very sensitive to pressures, the use of the fluid inclusion geobarometer can be considered to determine the depth of mineralization. During prognosis and prospecting of deep-seated granite-related polymetallic ore deposits, it is important to look for the top belt or cupola of hidden intrusions.