The Metallogenic Characteristics And Deep Prediction Of Jinwozi Gold Deposit In Hami, Xinjiang Province

Jinwozi gold deposit is located in the southeast of Hami, Xinjiang province, about 230 kilometer apart. The geotectonic position of Jinwozi is in Beishan rift zone in Malian well complex syncline core, belonging to the Beishan metallogenic belt Jinwozi- Zhaobishan metallogenic subzone. After many years of exploration and study, the proved reserves is nearly exhausted. To strengthen the research of mineralization characteristics, to guide deep and blind ore prospecting, It is the key factor for the sustainable production of mine area to strengthen the research of mineralization characteristics and prospect deep and blind ore. Based on the systematic analysis and investigation, the research results are completed through field geological survey and indoor comprehensive analysis and research. Mainly to achieve the following new results and understanding:The petrogeochemistry study shows that the granodiorite and monzonitic of Jinwozi granite belong to metaluminous to peraluminous granitoids of high K calcalkaline. Trace elements of the granite are riched in high Zr and depleted Ti. The REE distribution patterns show that the granite is characterized by negative Eu anomaliies and belong to the LREE-rich type. The MgO mass percent of biotite in granite is lower than six percent. Those phenomena indicates that Jinwozi granite belongs to crustal melting S-type granites and the materials derived from crustal. The diagenesis age of Jinwozi granite was distributed in(410-426)Ma and(441-446)Ma, representing two magmatic activities potentially. The age of detrital zircon of quartz sandstone of Jinwozi Formation is the same as the diagenesis age of Jinwozi granite, combined with the characteristics of stucture of fabric and rock. It indicates that one of material source of quartz sandstone drived from Jinwozi granite.Joint quantitative studying and tectonic stress analysis suggest that the principal stress directions are NWW(280°~290°), NW(300°~310°) and NNE(20°~30°) in the mining area. Studying on the regional tectonic evolution process and large deep fracture formation and activity time suggests that NNE direction stress is related to Early Paleozoic volcanic arc – Continent Collision Orogenic; NWW and NW direction stress is related to the formation, closing, sinistral strike-slip of Permian rift. NW direction stress is the largest influence for mineralization. Influenced by the force, mining area occur thrust-nappe structure, The strong strata deformation makes Au element activated and enter the ore-forming hydrothermal, forming ore in secondary fractures.Based on the study of ore-forming fluid inclusions of Jinwozi, the temperature of the inclusions is about 230~380; salinity is from 2 to 9 equiv wt.%Na Cl; and the density is from 0.60 to 0.95 g/cm3. The ore-forming fluid is featured by medium-low salinity temperature. The average ore-forming pressure is 125 Mpa and the average mineralization depth is 4.8km. The gas composition of the inclusion mainly is CO2 and a little amount of CH4,H2 S,N2,H2. The two-phase fluid composition is H2 O and three-phase fluid phase composition is CO2、H2O tested by laser Raman probe. Combination with analysis of hydrogen and oxygen isotope analysis, it is mixed with ore-forming fluid is magmatic water, metamorphic water and rain.By sulfur isotope and lead isotope analysis, the study discussed the sources of ore-forming materials. The data suggest that the two kinds of ore-body occurrence have the same source of sulfur. Sulfur come from Jinwozi granodiorite through eluviation; Pb isotope data suggest that metallogenetic materials come from upper crust strata, Meanwhile, a few deep source join in materials. The above shows that the whole process of mineralization is closely related to orogenic belt.The paper summarized main ore-controlling factors, mineralization era, source of ore-forming material and fluid source in deposits.The mineralization processes is: It is forming a low-angle thrust ductile shear zone with rift closed of Beishan during the end of the Late Paleozoic- Early Triassic early in Jinwozi area. Deep ductile shear metamorphic strata and causing intense deformation,. Au, SiO2, K, Na and some active components are taken from strata, mixing with deep magmatic hydrothermal mineralization,and forming the mixed hydrothermal minerals in the rift closure process. Hydrothermal is rising in rock crevice in Jinwozi, forming quartz vein type gold deposit; or placing in the ductile broken belt in strata,forming 210 gold deposit.Using of primary halo concentration index method, the axial sequence of 3+4 quartz vein was Co-Ni-Mo-Cr-W-Hg-Cu-Bi-Au-Pb-Zn-As-Ag-Sb and the 4 quartz vein was Cr-Ni-W-Co-As-Ag-Au-Mo-Cu-Pb-Bi-Zn-Hg-Sb. Primary halos spatial space model is built by the axial zoning sequence and the primary halo zoning evaluation v alue. There is a great prospecting space of deep orebodies analysed by a lot of front halo elements in the bottom of the orebodies.