Geochemical Characteristics And Deposit Genesis Of Jiaojia Gold Deposit In Shandong Province,China

The Jiaojia gold deposit is located in the northwest of the Jiaobei uplift,the north wing of the Laizhou-Qixia anticlinorium,and the secondary fault-Jiaojia fault of the Yishu Fault on the east side.In this paper,we have studied the geological charcateristics of ore deposits,alteration zone division,alteration zone migration,gold bearing mineral type and ore deposit geochemistry of the Jiaojia gold deposit to analyze the relationships between the gold bearing minerals and mineralization and alteration and mineralization,in order to provide reference and help for further study of the deposit.Based on the observation under the field and microscopic of the deposit,the ore body can be divided into seven alteration zones.Besides,this paper have summarized the migration law of the altered zone and the relationship between the alteration process and the alteration and discussed gold mineralization baesd on the geochemical characteristics of the alteration zone.It is believed that mineralization is proportional to the strength of rock fracture and the strength of alteration,and the silicification and pyrite mineralization are most related to the Au mineralization.The characteristics of gold bearing mineral typomorphic of the Jiaojia gold deposit shows that the euhedral and subhedral pyrite have no gold,gold average grade of the cataclastic pyrite is 0.05%,and the highest gold content of the xenomorphic pyrite can up to0.15%.The chalcopyrite of Jiaojia Gold show a characteristics of wealthy sulfur and cooper,low iron and loss arsenic.The average content of sulfur is 34.73%,the average content of copper is about 35.37%,the average iron content is about 29.36%,and the content of arsenic is only about 0.02%.The correlation analysis and scatter plot shows that Au was correlated with many elements.Through the study on fluid inclusions,the Jiaojia gold deposit is a moderate temperature deposit,the ore-forming fluid is CO2-H₂O-NaCl-CH4 system,and its main metallogenic temperature is 170.2 to 358.1?,salinity is 2.04% 10% NaCl,eqv,the average salinity is6.64% NaCl,eqv.Based on the analysis of hydrogen and oxygen isotopes,it is considered that the ore-forming hydrothermal is mainly a mixture of magmatic water and metamorphic water,of which the magmatic water is the principal component.The characteristics of S and Pbisotopes show that the sulfur in Jiaojia gold deposit is not only one of the mantle sulfur or the sulfur in the crust,but also the mixture of the two kinds sulfur.The Pb-isotope composition of ore deviates significantly from the crust,with a little from the mantle.In conclusion,the genetic type of the deposit belongs to the low temperature altered rock type-hydrothermal vein type gold deposit,which was controlled by the fault structure.