| Shancheng gold deposit, located in Qixia City, Shandong Province, tectonically,is situated in south of Qixia-Penglai metallogenic belt, Jiaobei Uplift, which belongs tothe North China plate. The Qixia-Penglai metallogenic belt, facing the Muping-Lushanmetallogenic belt on the west, while the Zhaoyuan-Pingdu metallogenic belt on the east,is an important Au-Cu-Mu polymetallic metallogenic zone in Jiaodong Region, and hasascendance on regional metallogenetic condition.The strata exposed in the mine area is sample, mainly Archean Jiaodong Group orCenozoic strata, and distributed in form of inclusion or skirt-zonal on the magin of Qixaisuper-unit. Magmatic rocks are widely distributed, mainly is Late Archean TTG rockseries, belonging to Huilongkuang unit, Qixai super-unit. Owing to superimposedreformation of amphibolite facies metamorphism and ductile shear, it formed a setof band, stripe-like, geissic schistosity-developing grey granitic gneisses. Dike rocksdeveloped very well during Mesozoic Yanshanian, lithology is mainly dioritic porphyriteand lamprophyre, while its lower is hidden granitic complex body, The ore-body arehosted by Qixai super-unit. Regional tectonic is complex, superposition intergrowth ofthe earlier nearly EW-or NW-striked ductile shear zone（equivalent to the originaldivision Qixia anticlinorium consisting of Precambrian strata） and the later NE-or NNE-fault, the fault, closely related to Shancheng gold deposit is Qixia ductile shear zone andfault.The main metallic mineral are pyrite, chalcopyrite, sphalerite, galena, library Huibismuth copper lead, krupkaite, kustelite and electrum, and the gangue minerals is quartz,ankerite, mica, chlorite and epidote. Ore textures are mainly cataclastic textures, euhedraltexture, hypidiomorphic texture, including texture and metasomatic relict texture. Ore structures are disseminated structure, veinlet-disseminated, crumb structure. Alteration ismainly silicification, iron dolomitization, potash feldspathization, sericitization,pyritization sericitization, carbonation, chloritization, epidotization and so on, amongthem, silicification, sericitization and pyritization sericitization are closely associatedwith mineralization.In the mine dioritic porphyrite and lamprophyre develop very well, and form hugedike rocks belts, geochemistry studies show they are a set of intermediate-basic dikes,characterizing high alkali and low Ti, lamprophyres are mainly calc-alkalic spessartite,The dike rocks have the characteristics of enrichment in LILEs and LREEs, whileshowing depletion in HFSEs and HREEs. Lamprophyres should be originated from partialmelting of enriched mantle metasomatized by fluid in subduction belt, during its risingprocess, were not obviously contaminated with crustal material, and formed in island arcscalc-alkalic environment. The lamprophyre from Shancheng gold deposit show faintrelationship with gold mineralization, but it does not eliminate the possibility of providingpart of ore-forming materials, heat and emplacementplaces.Study on fluid inclusions of Shancheng gold deposit shows that the ore-forming fluidhas characteristics of low salinity（2.62～7.31wt%NaCl.eqv） and low density（0.660.98g/cm3）, it is a NaCl-H2O-CO2system that is rich in H2O and CO2, during theore forming process fluid immiscibility occurred. The main metallogenic temperature isestimated to be280℃320℃, the main value of pressure is80120MPa, metallogenicdepth is worked out to be7.309.11km.The δ34S value of pyrite from Shancheng gold deposit changes in the range of+3.7‰to+6.4‰, which shows that sulfur isotope composition has positive deviating fromthe meteoric sulfur，and the δ34S value changes in small range, with obvious tower styledistribution, showing that the mean value of sulfur isotope is high, the sulfur sourceshave certain inheritance of Guojialing and Linglong granites, combined with wall rockcharacteristics we could speculate that the mineralization of Shancheng gold deposit arecaused by granitic magma which is from mantle or crust-mantle mixture, anatexismetasomatism of cratonization continental nucleus complex and TTG rock series, that is rich in Au. Study on H-O isotopes and fluid inclusion indicates ore-forming fluids aremainly mantle fluids and magmatic water, accompanied by slight participation, whilefluid phase separation occurred in the mineralization process, in other words, theNaCl-H2O-CO2fluid system is changed into H2O-NaCl and CO2-H2O fluid systems,boiling and fluid immiscibility occured in the mineralization process with characteristicsof CO2escape.The Shancheng gold deposit underwent four ore-forming stages: Ⅰirondolomitization-quartz stage;Ⅱpyrite-quartz stage; Ⅲp olymetallic sulfide-quartzt stage, itis the main ore-forming stage;Ⅳcarbonate-quartz stage.According to metallogenic background and characteristics, we hold that the depositbelongs to mesothermal vein-type gold deposit, hosted in Archean TTG rocks, and can beclassified as mesozonal orogenic gold deposit, proposed by Groves （1998）.The diagenesis and mineralization of Shancheng gold deposit has thecharacteristics of protracted nature and polyphyleticism. The dominant metallogenicfactors are Mesozoic Late Yanshanian tectonic and magmatic activities, metallogenicmaterial are derived from crust-mantle mixed, but mainly from mantle, the deposit typeis mesothermal vein-type gold deposit.The orebodies of Shancheng gold deposit are controlled by left lateral reverse fault,orebodies have segmented enrichment regularity on both strike and verticaldirection, industrial occur in partial extensional parts, that strike northwards and dippslowly. The orebodies of No.Ⅰ have NE-direction lateral trending, while those of No.Ⅷshow no obvious lateral trending. |
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