| Author:Guo JiaSupervisor: Professor Sun Jinggui （Jilin University）Speciality: Mineralogy， Petrology， Mineral depositsSishanlinchang gold deposit, located at the north segment of the polymetallicmetallogenic belt on the Taipingling uplift, is a typical gold-pyrite-sulfide quartz veintype gold deposit in Heilongjiang province, hosting in the brittle fracture of thePaleozoic metamorphic rocks. Base on the formers’research, we make a study on oregeology, geochemistry, fluid inclusion and geochronology. The following conclusionshave been reached:1. According to the research on the signature of ore geology, we advocate thatâ… -â…¡#ore-body host in the contact zone between the Neoproterozoic carbon mica-quartz schist formation in Yanwangdian group of Huangsong complex and thecretaceous dioritic porphyrite vein. The orebodys have a close relationship with thedioritic porphyrite. â… #ore-body hosts in the NNE fault structural belt along thecarbon mica-quartz schist formation, quartz veins and other altered tectonic rocks. Inthe metallogenic process, there is Multi-phase ore-forming structure, for example,late auriferous quartz veins cut the early-bearing quartz vein breccia and thephenomenon of sliding pieces along the fault. â…¡#ore-body suit on the â… #ore-body about40m-130m, at the middle part of structural belts, and deposit in thequartz altered tectonic rocks.2. The metallogenic process has been divided into four phases:（1）siliconization-quartz stage, as the product of early metallogenic fluid;（2） quartz–arsenopyrite stage, charactered by the mass arsenopyrite and pyrite;（3） Polymetallicsulfide-quartz stage, as the main mineralization stage of Sishanlinchang gold depositand charactered by the present of quartz, arsenopyrite, pyrite, chalcopyrite, sphalerite,galena, native gold, kustelite and calcite. In this stage, the metallogenic fluid fill andreplace the altered structural rocks formed in the early stage, and produce theauriferous quartz veins and altered rocks composed by disseminated pyrite, galenaand Polymetallic quartz sulfide veinlets;（4） Calcite–quartz stage, charactered by thepresent of calcite and quartz. Based on the study of the fluid inclusions, the homogenization temperature is150-310℃, with the ore-forming fluid salinitybetween4wt%NaCl and13wt%NaCl and the density of the ore-forming fluids of0.73g/cm3to0.91cm3. As the mentioned above, Sishanlinchang gold deposit has themetallogenic fluids characters of middle salinity, low density and middle temperature.According to the stable isotopes, metallogenic material mostly come from theCrust-mantle mixing and S isotope have a mantle resource. δ34S is similar between theauriferous quartz veins and the dike rock and suggest that the metallogenic materialpartly come from the dike.3. Diorite-porphyrite in the zircon U-Pb dating can be divided into six groups,and respectively was1057±9Ma,199±2Ma,144-148Ma,115±2.7Ma,111.6±1.7Ma（n=6，MSWD=0.55, probability=0.77）and107.3±2.8Ma（n=3，MSWD=0.088,probability=0.92）.And with the development of the regional thermal event ofmagma initial conditions determined diorite magma in place in115-107Ma.Andthenmagmatic evolution was underwent the strong contamination by granitic rock of theMesoproterozoic and the early Jurassic. After that time mineralization occurred in lateEarly Cretaceous into Late Cretaceous stage and its background of diagenesis andmineralization was related to mid-acid granitic magmatism within the Ring of thePacific plate. |
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