Discussion On The Geochemical Characteristics And Mineral Sources For Minerlization In JinChangyu Gold Deposit Of Hebei Province

Jinchangyu mine is one of the crisis mines, this paper is funded by ?National crisis mine replacement resources prospecting project?.Based on the field investigation and indoor analysis,combining with the mineral deposits geology? petrology?fluid geochemistry?stable isotope geochemistry?geochemical and other multi-disciplinary knowledge,in order to carry out a comprehensive study on the relationship between stratum-construction-magma-fluid characteristics and their contribution to the mineralization of Jidong gold enclave.Stable isotope geochemistry can trace the fluid source and the change of their physical and chemical properties; by major and trace element geochemical,we can get the source of minerals and enrichment process; we maintain gold material sources of jinchangyu by use of gold-bearing analysis both of the rock and stratum. Through the above research, we achieve the following understanding and research results:(1)Through the analysis of major elements of qingshankou rock mass, we believe the body of qingshankou rock mass is monzonitic granite, followed by granodiorite and moyite. The granodiorite underground the gold mine and qingshankou granodiorite body may be homologous product.As the evolution of magma, the femic dark minerals reduce, gradually toward to the change in potassium-rich, silicon-rich and alkali-rich, the intensity of magmatic fractional crystallization iincreases.we come to the conclusion that the granodiorite and the monzonitic granite are products of homologous magma evolution by REE research. The distribution patterns of qingshankou granite appeared on the negative Eu anomalies, indicating that in the process of fractional crystallization, feldspar separated from the felsic magma or feldspar remained in the source region during the melting process,there is a gradual HREE enrichment trend.(2)Characteristics of REE patterns show that alteration of amphibolites form the chlorite schist,they are homologous,but the sericite chlorite schist and the chlorite schist are non-homologous.(3)Through the study of trace elements in the ore body and the peripheral rocks, the content of Au?Ag?Cu?Pb? Zn in chlorite schist is gradually increased from the surface to the underground, while in sericite-chlorite schist, content of Au, Ag, Cu, Pb is decreased, and Zn is increased.(4)Feature of hydrogen-oxygen isotope?sulfur isotope and lead isotope show the ore-forming fluid of jinchangyu is derived from magma, and the hydrothermal fluids are originated from the deep.(5) Magmation of yanshan period has brought a lot of hydrothermal fluids, they interact with surrounding rock (chlorite schist), this leads to the chlorite sericitization, which changes the nature of the ore-forming hydrothermal, finally,the gold precipitated and formed gold ore bodies together with pyrite.