| Tudui-Shawang gold deposit is a large important deposit in the northeast range ofJiaolaibasin, it is the important part of Muping-Jimometallogenic belt which is located inGuocheng country, Haiyang city, ShandongProvince. In Late Mesozoic, dynamicenvironment of Jiaodong area transform from the NW-SE squeeze to the NW-SEextension, the surface crust extending stripped and formed depression, Jiaolai region intothe important metallogenic stagesThe regional strata have the Archean jiaodong Group, the Proterozoic jingshan Group,Mesozoic laiyang Group, qingshan Group, wangshi Group and Cenozoic quaternarysystem. Magmatic rocks are widely distributed in this area, mainly in the fine grainedmonzonitic granite, rock mass is presented ligulate on the whole, intrusion in thepaleoproterozoic jingshan old strata. Mesozoic dike rocks are well-developed, mainlysillite, dioritic porphyrite, lamprophyre, granitr porphyry, granodiorite, syenite. Trend aremainly NNE、NE, strike NW, dip angle are mainly70-80°.The mining area are development with faults, there are mainly detachment tectonicsystem, Guocheng fracture zone and its secondary fault, fissure zone on his footwall.Detachment tectonic’s hanging wall is given priority to brittle deformation in the processof stretching, forming some normal fault are parallel to the detachment fault, sametendency, dip angle between5°-63°. Guocheng fracture zone is40km±at length, the width rangs from6m to20m, and its widest point up to30-40m. Occurrence of280°-310°∠50°-80°. Guocheng fault’s hanging wall is the Mesozoic laiyang Group stratum, footwallis paleoproterozoic jingshan Group and Muniushan rock mass. Rock crushing strongly infault, with fault breccia and fault gouge.Mining area has delineated58orebodies, Tudui gold area has34ore bodies. Orebodies are controlled by detachment structure system, mainly in marble and grain of rock,present vein-like, Stockwork, layered output. Orebodies are mainly trend NE, strike295o±,dip angle5-30o. Ore types are mainly protogenesis sulfide ore, with a small amount ofoxidized ore. Metal mineral is mainly pyrite, a small amount of pyrrhotite, chalcopyrite,sphalerite, galena, native gold, electrum. Nonmetal minerals are mainly potassiumfeldspathization, silicification and carbonatization, chloritization and sericite. Orestructure are mainly idiomorphism, xenomorphic and cataclastic structure. Ore structureare mainly vein-like, Stockwork, disseminated.Shawang gold area has twenty-four orebodies, ore bodies are controlled bydetachment structure system, the main ore-bearing rock is brecciaous, pyritizedmonzonitic granite, present vein-like,net vein, layered output. The orebody general trend295°±, strike18°±. Ore types are are protogenesis sulfide ore, with a small amount ofoxidized ore. Metal mineral is mainly pyrite, a small amount of pyrrhotite, chalcopyrite,sphalerite, galena, native gold, electrum. Nonmetal minerals are mainly potassiumfeldspathization, silicification and carbonatization, chloritization and sericite. Orestructure are mainly idiomorphism, xenomorphic and cataclastic structure. Ore structureare mainly vein-like, Stockwork, disseminated.Tudui-Shawang gold deposits’ wall rock alteration are widely distributed, commonalteration types are mainly potassium feldspathization, silicification and carbonatization,chloritization and sericite. Wall rock alteration in the area has the characteristics ofhorizontal zoning. From ore bodies to the lateral, appear in turn sericite, silicification,chloritization and potassium feldspathization.Tudui-Shawang gold deposit metallogenic period is divided into hydrothermal stage and supergene oxidation stage. The hydrothermal mineralization period is divided intofour metallogenic stages, namely①quartz-pyrite stage;②gold-quartz(sericite)-pyritestage, is the main gold mineralization stage, high gold content;③quartz-polymetallicsulfide stage, formed a small amount of gold;④quartz-carbonate stage.Fluid inclusion studies have shown that Tudui-shawang gold deposit ore-formingfluid is middle-low salinity (4.3%~12.6%wt%NaCl.eqv）、low density（0.64～0.97g/cm3）、riched in CO2of CO2-NaCl-H2O system. Metallogenic temperature is from280℃to320℃, ore-forming pressure is81~94Mpa. Metallogenic depth is7.39~7.98km. Hydrogenand oxygen isotopic test and analysis shows that ore-forming fluid is the mantle fliudwater, a small amount of magmatic water and meteoric waters. Lime sulfur, lead isotopicresearch shows that ore-forming materials are from lower crust and upper mantle magmamixing zone, in the process of upward, extracted the ore-forming material in the jingshanGroup.In conclusion, this paper preliminarily determines the Tudui-shawang gold depositsgenetic types are involved in mineralization of the mantle fluid mesotherm hydrothermsolution deposit. |
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