Genetic And Prospecting Mineralogy Studies Of Quartz-type And Altered-type Gold Deposit In Jiaodong Region

The Jiaodong gold belt is an important gold production base in China. The gold deposits in Jiaodong are mainly divided into three types:quartz vein type, altered rock type and interlayer slippage type. At present, little studies have been carried on the similarities and differences of the different types gold deposits in Jiaodong and the similarities and differences of east and west of Jiaodong. This paper makes a systemtic contrast on the similarities and differences of gold deposits in Jiaodong region.The studies of pyrite composition characteristics using δFe-δS,(Fe+S)-As,δFe/δS-As, Co-Ni-As and (As+Sb+Ba+Ag+Hg)-(Au+Bi+Cu+Pb+Zn)-(Ti+Cr+Co+Ni) systems and of quartz composition characteristics using Na-K-Al and (Na+K)-Al systems consistently showed that gold deposits in Jiaodong are magmatic-hydrothermal genetic type and also showed that the order of pyrite impurity content from big to small are altered rock type, interlayer slippage type, and quartz vein type. The (As+Sb+Ba+Ag+Hg)-(Au+Bi+Cu+Pb+Zn)-(Ti+Cr+Co+Ni) systems of pyrite composition characteristics showed that ore-forming depths got deeper from interlayer slippage type to quartz vein type to altered rock type. East was with shallower ore-forming environment than west in Jiaodong region.The results of rare elements characteristics in pyrite and quartz showed that ore-forming environment of reduction got weaker from interlayer slippage type to altered rock type to quartz vein type. The ore-forming environment of reduction got weaker from western alter rock type to eastern quartz vein type to western quartz vein type.The results of pyrite S isotope characteristics showed that the δ34S values got bigger from quartz vein type to interlayer slippage type to altered rock type. This reflected that the ore-forming environment of oxidizing got weaker from quartz vein type to interlayer slippage type to altered rock type. As a whole, east was with stronger oxidizing environment than west in Jiaodong region. The S isotope thermometer showed that the ore-forming temperature of Jinchiling gold deposit (west in Jiaodong) was higher than that of Denaggezhuang gold deposit (east in Jiaodong). The studies of quartz fluid inclusions showed that or-forming fluid was middle-low temperature, middle salinity fluid belonging to weak acid and reducing environment. The average values of homogeneous temperature got lower from western quartz vein type (283.55℃) to eastern quartz vein type (230.52℃) to interlayer slippage type (210.37℃). The pH values of interlayer slippage type got much closer to neutral for the more precipitation mixed. The lgfo2of interlayer slippage type was the smallest for the strongest ore-forming environment of reduction.The results of stable isotope showed that the hydrothermal ore forming solution mainly came from magmatic fluid and atmospheric water, and magma with major crust and minor mantle substances.The metallogenic materals mainly came from the magma and the host wallrock.In a conclusion, ore-forming environment of reduction got weaker from interlayer slippage type to altered rock type to quartz vein type. East was with stronger oxidizing environment and deeper depths than west in Jiaodong region. The genetic mineralogy characteristics among interlayer slippage type to altered rock type to quartz vein type were much different and could be used to distinguish each type gold deposits.