The Kiloton Class Jiaojia Gold Deposit in Eastern Shandong Province and Its Genesis

摘要: The recent deep prospecting results in the Jiaojia area of Eastern Shandong Province indicate that ore field composed several individual gold deposits as previously suggested is actually an ultra-large deposit. This deposit covers ∼40 km2, and shows a structural control by fault its secondary faults. Gold orebodies generally occur along same mineralization-alteration belt, main intersect with each other or exhibit parallel overlapping distribution. deposit's reserves are estimated to be 1, 200t gold, being first more than 1000t China. No. I-1 orebody Shaling-deep Sizhuang blocks holds greater 350 t, 29 percent total reserves, followed I Matang-Jiaojia exceeding 150t reserves. mainly occurs footwall fault, presents zoned patterns mineralization, alteration structures. strongly mineralized zones agree altered tectonically fractured zones. These display strataform-like, veinlike lenticular shapes, show characteristics pinching out reappearing, branching converging, expanding shrinking. commonly positions where strike changes gentle locations dips changing from steep gentle. plane ore-controlling tend surface deep. plunge southwest, angle 45°–60°. Orebodies near have resource those away zone. slant depth larger length direction; become thick grades low shallow area. Ore-forming fluids H2O-CO2-NaCl±CH4 type medium-temperature moderate salinity. Sulfur isotopic values (δ34SCDT) for ores range between 11.08‰ 12.58‰, indicating mixed sulfur sources; hydrogen (δDV-SMOW) –83.68‰ –116.95‰ oxygen (δ18OV-SMOW) 12.04‰ 16.28‰. isotopes suggest ore-forming originated primary magma, mixing large amount atmospheric water during late stage. associated magmatic activities which mantle-crust-mixed source, also share some similarities orgenic epithermal hydrothermal deposits. Because unique metallogenic features formation setting different types world, we call it Jiaojia-type kiloton class related fluid activities, extension detachment resulted thermal upwelling magmas. strong middle stage early Cretaceous lead active fluids, provided abundant materials depsoits. Moreover, many extensional structures resulting crustal favourable space positioning.