Geology, Geochemistry and Genesis of the Hongshijing Gold Deposit in Ruoqiang,Xinjiang

The Hongshijing gold deposit, which occurs in the Middle and Late Carboniferousvolcanic and pyroclastic rocks, is of the brittle-ductile shear zone type controlled by a rift belt.The Hongshijing gold deposit is one controlled by a brittle shear zone located in the Late Paleo-zoic rift zone. The altered-rock type and quartz type orebodies are contained in the gold-bearingformation, which consists of basalt and tuffaceous sandstone. The major mineralizing stage is at267 -261 Ma and reiteration mineralizing stage at 220 -209 Ma. The ore minerals include py-rite, magnetite, copper, bornite, ferrohydrite, native gold, and the gangue minerals includequartz, sercite, calcite, Fe-dolomite, leucoxene, anorthose, biotite, baria, cajuelite, andagustite. The wall rock alteration associated with gold mineralization comprises silicification,carbonization, pyritization, sericitization and chloritization. The contents of gold are 2.4 × 10-9in the gold-bearing formation, 5.7 × 10-9 in the tuffaceous sandstone and 1.4 - 1.5 × 10 9 inthe basalt. Au is associated with Te, Se, Ni, Cu. Au = 74.331 × Te + 0. 0335 × Ni - 0.0211 ×Cu- 2. 650. Geochemical investigations revealed that the mineralizing materials came from thebasalt and tuffaceous sandstone in the gold-bearing formation. Under the action of ductile brittleshear structure, the gold-bearing formation was metamorphosed and altered, and the ore-formingmaterials activated, migrated and mineralized. The mineralizing fluid shows three mineralizingstages, with the characteristics of middle to low temperature (381 - 115℃ ) and middle to lowmass fractions of NaCl (2.18% -16.77% ). The fluid is of the Ca2+ -Mg2+ -Na+ -Cl- type andH2O-NaCl system. According to the data from hydrogen and oxygen isotopic composition (δD =- 114.6‰ - - 68.8‰, δ 18 OH2O = - 2.47‰ - 5.91‰), the conclusion can be drawn thatthe mineralizing fluid of the Hongshijing gold deposit was a kind of mixed hydrothermal solutioncomposed mainly of meteoric water , magmatic water and formation water in bas