Geochemical Characteristics Of The Gold Deposits Onzhaoping Fault Zone And Its Implications

The Jiaodong gold-centralized area is the largest gold production area in China, and the Zhaoping gold ore belt is the most famous. There are many large gold deposits along the Zhaoping fault zone. This paper chooses Linglong gold deposit, Dayingezhuang gold deposit and Xiadian gold deposit to sample the wall rocks and ores and discusses the geological structure, material source and so on according to the study of petrology, major and trace elements, rare earth elements and zircon U-Pb isotope dating and combining to the previous studies in the tectonic background, geochemistry.The studies of major elements show that Rittmann index (δ) of the most rocks is below3.3which belong to calcium-alkali magmatic series and only the few is between3.3and9which belong to alkaline series. All the ratios of Al2O3/（Na2O+K2O+CaO） are greater than1showing peraluminous.The studies of trace elements show that they are characterized by enrichment of LILE, depletion of HFSE and have the similar trace element curves which indicate they have the continental curst materials or the reconstitute materials from volcanic arc. In addition they are characterized by positive Pb anomalies relative to continental curst and negative Nd anomalies which show that they are maybe subduction zone lava or typical continental curst rocks and hybridism occurs in the process. Meanwhile, the results indicate they maybe have the same material source, evolution direction or evolution form.The studies of rare elements show that most of the samples are rich in LREE, depleted in HREE, with some negative Eu anomalies (especially gold ores) which maybe relate to gold mineralization. And they have similar REE patterns which indicate they maybe have the same material source or evolution form. The lava mixed mantle substance with curst in the process of formation.The studies of zircon U-Pb isotope dating show that the ages of Linglong rock mass, Dayingezhuang rock mass and Xiadian rock mass were151.6±2.3Ma,170.7±2.9Ma and1840±20Ma. Most of the ratio of Th/U is greater than0.1. And the cathodoluminescene (CL) images of the inner part of the zircons show oscillatory zoning, indicating a magmatic origin.