Mo-Au Polymetallic Minerogenetic Series And Prospecting Direction In Xiong'ershan Region

The North China Craton(NCC)has excellent metallogenic geological conditions,and is an important mineral produce area in China.As a part of the NCC,the Xiong' ershan region has many Mo-Au polymetallic deposits.In recent years,numerous fluorite deposits,closely related to the Mo-Au deposit,have been discovered in the area.Previous studies focus on minerogenetic series of polymetallic deposits,while lack of the correlation between fluorite deposits and polymetallic deposits study.Based on the metallogenic characteristics study,we conducted systematic analyses on isotopic geochronology,fluid inclusion,H-O-C-S-Pb isotopes and rare earth elements to discuss the relationship between the fluorite deposits and polymetallic deposits.Furthermore,we summarized the minerogenetic series,and proposed a regional mineralization model and prospecting direction.The main achievements and innovations of this work are as followed:1.In this research,the Early Cretaceous deposits in Xiong' ershan region are classified into three types:porphyry-breccia type Mo-Au deposits,altered-vein type Au deposits and hydrothermal vein type fluorite deposits.From the Early Cretaceous granite as the center outward:porphyry-breccia type Mo-Au deposits? altered-vein type Au deposits?hydrothermal vein type fluorite deposits.These deposits are genetic related and belong to the same tectonic-magmatic-hydrothermal mineralization events.2.The pyrites from the Yuanling vein type Au deposit yielded Rb-Sr isochron age of 121.5±1.5 Ma,and the fluorites from Madiu and Angou hydrothermal vein type fluorite deposit yielded Sm-Nd isochron age of 118.9±7.8 Ma and 119.1±4.3 Ma,respectively.Combining with the previous researches shows the porphyry-breccia type Mo-Au deposits mainly mineralized at 135?129 Ma,followed by the altered-vein type Au deposits(129?120 Ma)and hydrothermal vein type fluorite deposit(?119 Ma).3.The fluid inclusion and C-H-O istopes analysis shows that the initial fluids of the porphyry-breccia type Mo-Au deposits were mainly derived from a high temperature and high-medium salinities magmatic source.The initial fluids of the altered-vein type Au deposits were mainly derived from a high-medium temperature and medium-low salinities magmatic source.The initial fluids of hydrothermal vein type fluorite deposits were mainly derived from a medium-low temperature and low salinities meteoric source.The main metallogenic mechanism of the porphyry-breccia type Mo-Au deposits and the altered-vein type Au deposits was fluid boiling,and the main ore-forming materials was of magmatic source.The main metallogenic mechanism of the hydrothermal vein type fluorite deposits was water-rock reaction,and ore-forming materials was mainly sourced from the wall rocks.4.Based on the analysis of the above,we summarized the Early Cretaceous Mo-Au polymetallic minerogenetic series and regional mineralization model,and proposed the indicator of different types deposits for prospecting.We conducted systematic analyses on the fluorite typomorphic characteristics in polymetallic deposits and fluorite deposit,and proposed the indicator of fluorite typomorphic characteristics for prospecting.Furthermore,combining regional geochemical prospecting anomalies,we proposed the prospecting direction of different types deposits.