Mineral deposit model of Mesozoic porphyry Mo and vein-type Pb-Zn-Ag ore deposits in the eastern Qinling, Central China and its implication for prospecting

A decade of molybdenum deposits comprising several large-supper large ones have been explored in the past several years. At the same time a lot of vein-type Pb-Zn-Ag deposits are discovered, which are distributed around the porphyry molybdenum deposits, such as the Nannihu giant porphyry molybdenum ore district and the Donggou giant porphyry molybdenum deposit, a new property. These vein-type Pb-Zn-Ag deposits obviously exhibit a close relationship to the porphyry Mo deposits in space and time, sharing one ore system. The porphyry molybdenum deposits in the episodes of 156-137Ma and 125-114Ma represented by the Nannihu and the Donggou, are derived from anatexis of the mantle and crust, and the crust only, respectively. Although the two episodes of mineralization have differences of the ore-forming time and sources the mineralization zoning reflects a normal temperature-decreasing process around the high-fractionation granite plutons associated with the all porphyry deposits. On the other hand, the granite plutons are able to act as energy engines, which triggered to form the convective hydrothermal system. The hydrothermal solution in the system leached the ore-substances from the host rocks of carbonate and discharged them in the available structures, for instance, the extension locations of faults, and discordant boundary of the strata. In light of the basic characteristics of the ore system and understanding for the metallogenic process, we propose a new model to describe.