| Hongtoushan copper-zinc deposit is located in northeastern Liaoning Province, tectonically in the central of Tieling-Jingyu paleouplift,Liaodongtai anticline, eastern margin of North China. The strata are mainly Archean metamorphic rocks, exposed in Qingyuan palaeo-continent nuclei of different size and irregular pattern. Three greenstone belts can be divided according to their distribution and the location of the deposits, they are Shujigou- Hongtoushan greenstone belt, Dahuanggou-Bizigou greenstone belt and Gujiazi-Hongqishan greenstone belt.Strata in ore field is Hongtoushan formation in Anshan group, from lower to upper are thick amphibolite gneiss layer, garnet anthophyllite gneiss layer, biotite plagioclase gneiss (granulite) layer, thick hornblende-plagioclase gneiss layer and"thin interbeds". Original rock reconstruction of ore-hosted strata comes to the conclusion that the ore-hosted rock series is set of Calc-alkaline volcanic rock formation formed in tectonic enviroment of island arc—medium acidic volcanic rocks, volcano-sedimentary and sedimentary rocks.It has experienced three stages of structural deformation: the first structural deformation forming NEE-SWW closed inverted synclinal fold F1, NNE axial orientation, eastward pitching and SSE dipping of both flanks; the second deformation forming near SN wide vertical dumping folds F2 superimposing the earlier fold F1, fold axis is nearly upright; the third formation effected by NWW-SEE force bedding sheared the earlier folds. The orebodies deformed and replaced between layers, fold hinge (orebody) pitched rotationally, NW dipping at the top of hinge, NE dipping at the bottom, and the ore occurrence getting gentle.Magmatic rocks are tonalite, olive (gabbro), basalt, diabase, granodiorite, granodiorite porphyry, lamprophyre, pegmatite (nearby the ore bodies) as well as trondhjemite (periphery). Tonalite magmatic activity is important to this ore field, invading in large area (isotope age of 2800-2900Ma, Denggongquan, 1994), pushing, fusion, top erosion and metasomatism on the surrounding rock, so that the Hongtoushan greenstone rocks are exposed like island in the tonalite rock. Large amount of post-tectonic diabase wall cut fold and orebodies in SN direction.The ore bodies occur at the dumping side of the Hongtoushan vertical dumping fold, NEE axial direction, SE dipping, and 70°-85°of dip angle. Copper-zinc ore bodies occur in the "thin interbeds", and ore pillars present in fold hinge.Ore types mainly are massive and veinlet disseminated type. Major ore textures are separation texture of solid solutions, corrosion-metasomatism and fractured texture. Ore structures are mainly massive and veinlet-disseminated structure. Ore minerals are pyrite, pyrrhotite, chalcopyrite and sphalerite, small amounts of galena, cubanite, electrum, and rare molybdenite. Gangue minerals are quartz, biotite, plagioclase, anthophyllite, muscovite, zinc spinel, sericite, garnet, kyanite, sillimanite, staurolite and cordierite, etc.Alteration zoning: from disseminated orebodies outward developed tremolitization zone, muscovitation-sericitization-silicinization zone, chloritization zone and biotitization zone.By the study of fluid inclusions within massive ore and disseminated ore, some important physical and chemical parameters of mineralization are obtained. The fluid inclusions within quartz mainly contain NaCl-H2O solution of vapor and liquid two phases, with daughter minerals three phases. The shapes of the vapor and liquid two phases inclusions are oval, strip and other rule shapes, size are usually 8 ~ 15μm. The gas/ liquid ratio of these inclusions most about 15%, belonging to liquid-rich fluid inclusions; the saline daughter minerals-bearing polyphase inclusions in the shape of oval, strip and other rule shapes, size 8 ~ 16μm and the gas-liquid ratios of 10% to 15% range,Daughter minerals in fluid inclusions are most likely NaCl crystals. According to the temperature data of fluid inclusions, the depth and the salinity data of two types of inclusions were consistent. Average homogenization temperatures of fluid inclusions for the Massive ore is 216℃, average salinity is 24.6%, ore-forming fluid density is 1.06g/cm3, forming pressure are 30Mpa and depth of the ocean was 3.0km; disseminated ore homogenization temperature of fluid inclusions is 221℃, the average salinity is 27.4%, ore-forming fluid density is 1.06g/cm3, forming pressure was 33.0Mpa. According to depth of the ocean was 3.0km, the ore-forming average depth of the disseminated ore was 300m. It is show that the hydrothermal exhalative channel depth of not less than 300 meters below the surface.Sulfur isotope characteristics indicate that mineralization from early Archean submarine volcanism, the hydrogen and oxygen isotopes composition and chemical characteristics of the fluid inclusions indicate that ore-forming fluid is the ancient ocean sea water mixed with magmatic water.By the study of Hongtoushan copper- zinc deposits in tectonic environment, host rock, ore structure, alteration zone, ore bodies, ore material sources and so on, it is suggested that Hongtoushan copper- zinc deposits was Noranda type massive sulfide mineralization. And the mineralization model of Hongtoushan massive sulfide is as follows:New Archean period, about 2800Ma-2600Ma,the drift of the ancient land formed the subduction of oceanic crust, resulting in a strong undersea volcanic eruptions and forming a rich base metals of basic - neutral - acidic calc-alkaline volcanic rocks combination, constitute the Qingyuan ophiolite belt within a massive sulphide Cu-Zn deposit. In the intermittent period of volcanic activity, volcanic erupting hydrothermal water along the volcanic conduit leaching and replacing wall rocks, form hydrothermal ore water. Then,hydrothermal ore water rising to the sea, in the weak acid restore environment, form the primitive accumulation of sulfide layer and covered by the following clastic rocks, felsic volcanic rock.In the continental environment of late Archean (2500Ma) ,under the intrusion of TTG rock series,greenstone and massive sulfide ore (before-mentioned the initial ore) suffered with amphibolite facies metamorphism,deformation and plastic flow. In the turning side and the nuclear of the folds, ore bodies relatively thickening,and in the shear zone ore bodies is elongated to form a complex ore body.
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