| The Shujigou Cu deposit is located in the middle of Liaodong anticline Tieling-Jingyu palaeohigh which is in the eastern margin of North China, which occurred withinHongtoushan-Shujigou greenstone belt. The geological characteristics for Shujigou Cudeposit are similar to the Hongtoushan Cu deposit. The are volcanogenic massive sulfidedeposit Based on the project of China Geological Survey, we carryied out field geologicalinvestigation and indoor systematic study to the Shujigou Cu deposit, discussed mineraldeosit and geochemiscal characteristics, and determined genesisi of mineral deposit andpointed out further prospecting direction.The exposed strata of this area are mainly the Hongtoushan Formation ShujigouMember, and from the top down lithology are hornblende plagioclase gneiss, biotiteplagioclase gneiss,“thin alternating layer”, thick layered amphibolite gneiss andamphibolite pyroxene. The structure of the mining area includes nearly EW-trending andSSW-striking located in east aan closely and same tendency synform folds which formedin the Early Archean. The orebodies are closely related to fold structure. The magmaticrocks in the mining area are mainly compsed of dykes, and the type of rocks are mainlyolympic long pegmatite, K-feldspar pegmatite, diabase, diorite, granodiorite porphyry,hornblende lamprophyre rocks and so on. Among all the rocks, Olympic long pegmatite isclosely related to mineralization.The ore bodies presented as stratiform or stratoid occurred in interbed belt of theHongtoushan Group Shujigou Member biotite plagioclase gneiss and plagioclasehornblende gneiss. Ores occurs as massive structure and disseminated structure, and porphyroblastic texture, separation of solid solution texture, replacement texture andcataclastic texture. Metallic mineral are mainly composed of pyrrhotite, sphalerite, pyriteand Chalcopyrite. The good ore-forming elements components include Cu, Pb, Zn, Ag, Au,Co, Mo, Hg, Sb and so on. Wall-rock alteration is dominated by silicification andchloritization, secondly is sericitization and carbonatization. The alteration is closelyassociated with mineralization. The intensity of alteration is enhanced from wall-rock toorebody and hanging wall of orebody alteration is strengthened than footwall.The ore-bearing formation protolith for the Shujigou Cu deposit is a group of mid-acidvolcanic rocks, which is enriched in large ion lithophile elements, light rare earth elementsand incompatible elements, and slightly depleted in high field strength elements and heavyrare earth elements with high ratios of Th/Ta, Ce/Yb, La/Nb, La/Ta. The primitive mantlestandardized spider diagram of trace element model is similar to typical calcium alkalinearc basalt pattern with “three apophysises” shape. It indicate that the calc-alkaline volcanicrock group of the dacite, rhyolite andesite-basalt is derived from homologous magmaticdifferentiation and formed in island-arc environment. Gneissose granite, closely associatedwith mineralization, with characteristics of rich alkali, aluminum, silicon and low calcium,iron and magnesium, intensely rich K, Rb, Ba and Th, rich Ce and Sm, and significant lossTa, Zr, Hf and Ti. It is characterized by calc-alkalic rock series and formed in island-arcenvironment.The ore-forming fluid showed that inclusion from quartz is characterized by gas liquidtwo phase, and oval in shapd. The size range from4μm to14μm and mainly from5to10μm. The vapor liquid ratio range from15%to25%and mainly around20%. The fluidinclusion belongs to rich gas phase. The average value of homogenization temperature forfluid inclusions is179.8℃. The average value of salinity11.08wt%NaCl, and density is0.97g/cm3and ore-forming pressure is19.2MPa.According to metallogenic conditions and prospecting marks development situation,we considered that there is prospecting potential in the deep and periphery for theShujigou Cu deposit. The position of ore-bearing bed’s lithology, benefit of theconstruction site, wall rock alteration characteristics, geophysical aspects is represented by low resistivity, hgh polarizability and geochemical anomaly characteristics, which are allprospecting marks for the ore deposit. Comprehensive utilization geochemical surver onsoil, stream sediment, primary halos, halogen element and mercury element, and a seriesof geography survey on physical geophysical survey of TEM, CSAMT, electric-mediumgradient method and sounding of induced polarization method to exploration blind orebodies in deep and the same peripheral type deposit. |
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