Study On Metallogenic Differences Between Jinchangyu Gold Deposit And Yuerya Gold Deposit In Eastern Hebei

Large scale gold mineralization in Eastern Hebei is closely related to Mesozoic granitic magmatism in time,space and genesis.Igneous rocks occur near most gold deposits(such as Jinchangyu Gold Deposit),or ore bodies directly occur in igneous rocks(such as Yu'erya gold deposit).Although predecessors have done a lot of research work on the two gold deposits,the study on the physicochemical conditions of ore bearing magma in the two gold deposits is still very weak.On the basis of previous studies,through detailed field investigation,combined with indoor electron probe composition analysis,zircon U-Pb dating and zircon in-situ trace element analysis,this paper determines the metallogenic rock mass of Jinchangyu Gold Deposit,its formation age and magmatic source quality;Determine the magmatic source properties of ore-forming rock mass in Yu'erya gold deposit;The difference between the two metallogenic rocks is analyzed,so as to explore the metallogenic mechanism of gold deposits in Eastern Hebei.1.Through the interspersed relationship between different veins and the symbiotic combination of minerals,the Jinchangyu and Yu'erya gold deposits are divided into four different metallogenic stages.2.The main gold bearing minerals in the two ore bodies are pyrite,and the sulfur content is lower than the theoretical value by electron probe analysis.The contents of Co and Ni in pyrite show that the pyrites in Jinchangyu and Yu'erya belong to magmatic hydrothermal genesis,while the contents of As,Se and Te further indicate that the two deposits belong to hydrothermal deposits.Au and S elements belong to metal metallogenic elements,and their contents can indicate that they come from deep and are related to magmatism.3.Zircon U-Pb chronology shows that the diagenetic age of the albite closely associated with the ore body in Jinchangyu Gold Deposit is 191.9±3.8 Ma.The diagenetic age of granite in Yu'erya gold deposit is 173.8±3.9 Ma.The diagenetic age of diorite in Yu'erya gold deposit is 163.8±3.2 Ma.4.The trace element analysis of zircon shows that the content of light rare earth in the sample is deficient and the content of heavy rare earth is enriched,showing a right dipping distribution model,in which both are characterized by positive anomalies of Ce and negative anomalies of Eu.The larger Ce4~+/Ce3~+value indicates that the two ore-forming rocks are in a high oxidation state during crystallization.Therefore,it is speculated that high oxygen fugacity may be an important feature of the metallogenic rock mass of gold deposits in Eastern Hebei.