Genetic Mineralogy With Emphasis On Gold Prospecting Of DuJiaya Gold Deposit In Yantai Fushan Area, Jiaodong Region

Jiaodong gold deposit cluster in Shandong Province is the most important gold production base in China. Different from two famous gold deposit "Jiaojia deposit" and "Linglong deposit", DuJiaya gold deposit is a new type——interlayer gliding detachment zone type.DuJiaya gold deposit is located tectonically in the southeast margin of the North China craton, and in the central of Jiaobei uplift.where tectonic movement and magmatic activities are active. The diorite porphyrite and the quartz diorite porphyrite is related to the ore-forming genetically. The auriferous ore bodies which are controlled by the Northern east, the Eastern west fault and the thrusting fault, are in the complex of Fenzishan Gr.The alterations of wall rock related to mineralization were pyrilic phyllic,silicification, pyritization and so on..Mineralization phase contain beresitization phase, pyrite-quartz phase, quartz-pyrite phase, quartzpolymetallic-sulfide phase, and quartz-carbonate phase.The typomorphic characteristics of pyrite:The ratio of S/Fe is over 2 and the chemical composition shows that pyrites are poor in Fe; The P type is the domestic thermoelectricity type, and the thermal electricity coefficient display regular high-low-high style changes. Unit cell parameters are generally high; trace elements data presents that As, Sb, Pb and Zn concentrate in the upper part of ore body; Co/Ni content rate indicates the deposit have magamatic hydrothermal genesis characteristics.The data combining with REE and HFSE information indicates that the hydrothermal ore-forming solution is Cl-rich fluid.The component in the quartz fluid inclusions is composed of CO₂, H₂O, K⁺,Na⁺ and Cl^-.The homogeneous temperature is concentrate on 134～275℃. pH:4.52～6.10, Eh:-0.27～-0.35v, salinity:0.71～23.05 wt% NaCl, density:0.75～0.92 g/cm³ and mineralization depth: 5.04～7.19km.The study shows that or-forming fluid is middle-low temperature, middle salinity fluid belonging to weak acid and reducing environment. The curves shape of thermoluminescence of major metallogenic stages are one-peak pattern. The curve peak locations is 206.26～255.79℃.The lithology of dykes mainly composed of dioritic porphyrite,quartz dioritic porphyrite,and they are together with the orebody.quartz dioritic porphyrite.The CL images show clear internal morphology of zircons, and from core to edge, Zircon from two samples obtained 129.3±1 Ma and 129.4±5.6Ma LA-ICP-MS U-Pb age respectively, Combining the REE geochemical data, both have relatively oxidation and reduction of the two opposite the crystallization of environment, we concluded that they have the crust and mantle region respectively.The result of stable isotope show that the hydrothermal ore forming solution mainly comes 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.the host wallrock is from the lower Proterozoic group, such as Fenzishan group formation and so on.Based on the contour map of gold grade, the changes of ore body occurence,the typomorphic characteristics of typical minerals, and the contact relationships between different geological bodies in field, predicting target areas.