| Western Qinling is one of the important gold deposit areas of China.There are many types of gold deposits in the area, and a lot of previous researches had made a comprehensive study of those deposits. XiaoGouLi gold deposits as the West Qinling is unique quartz vein type gold deposits, but this research is relatively weak. In this paper,the author takes XiaoGouLi gold deposit as the research object,carried out a detailed study of the Geological characteristics and metallogenic regularity,as summarized in Western Qinling gold mineralization law provides raw data and data-oriented area while prospecting work indicates direction.During the field investigation, geological surveies in mining area have been operated in detial,and the ore body to deliver the characteristic as well as with the stratum,the structure,the magmatic rock spatial relations have been studied. At the same time,the auther took the thin section under the light microscope,chemical analyses and tests of major elements and trace elements, determination of fluid inclusions, stable isotope analysis, zircon SHRIMP U-Pb dating,dating of mineralized altered sericite,etc indoors. The regional geological features and metallogenic regularities were studied in detail,preliminary cognitions have been new acquired as follows:1 、 Granitoid geochemical test results showed that: granite porphyry is acidic,alkaline-rich,sodium-rich,peraluminous,calc-alkaline,I-type granites; Its REE pattern is enrichment LREE and loss HREE model,distribution patterns rightis,Eu negative anomaly,similar to I-type granites.Diorite porphyrite is neutral rock to slightly acidic, alkali-rich,sodium-rich, high-K calc-alkaline,weakly peraluminous,I-type granites; Its REE pattern is enrichment LREE and loss HREE model,distribution patterns gentle rightist,Eu negative anomaly,similar to I-type granites.2、Test on isotope age showed that: XiaoGouLi granite porphyry is 236.1 Ma, diorite porphyrite between the ages 201-212 Ma. There were formed during regime switching in late orogenesis.3、To estimate the magma crystallization temperature by zircon saturation temperature, granite porphyry magma formation temperature is lower than the diorite porphyrite magma formation,possibly granite porphyry magma source region shallower than diorite porphyrite magma source.4、XiaoGouLi gold deposit is located in the central of Xicheng ore field in the west Qinling Mountains. Ore bodies is occur in the hanging wall and footwall of granite porphyry dikes、diorite porphyrite dikes and Devonian strata that near the dikes. Ore bodies is controlled by ductile shear zone to the Near EW and the matching pieces crack and shear crack control. The single ore body formed by auriferous quartz that is vein, stockwork and dendritic. Its overall direction of EW, with zonal distribution along the ductile shear zone.5 There are quartz vein type ore and altered rock type ore in the XiaoGouLi gold deposit.It has some gold mainly as independent mineral and a small amount of silver gold mineral, the main gold bearing minerals are quartz, albite, calcite, dolomite and carbonate minerals. Gold and silver mineral inlay between the quartz grains and quartz grains, quartz grains and pyrite grains, quartz grains and ankerite grains and also inlay in the edge of quartz veinlets and veinlets derived from micro veins and intersections.6、The analysis results of sable isotopes of sulfur,hydrogen,oxygen in the XiaoGouLi gold deposits show that:ore-forming fluids are charactered by a mixed resource of magma water(mainly),metamorphic water and air water.Mineralizing materials have the characteristics of deep source.7 、 The deposit metallogenic age of 197.5Ma,slightly later than the age of iorite porphyrite; the ore of rare earth,trace element analysis and its chondrites(primitive mantle) standardized distribution patterns have the same scope and patterns with the iorite porphyrite. Combined with the geology of ore deposits and ore structure,XiaoGouLi gold deposit formation related to the magmatic activities,mineralization is closely related with the diorite porphyrite,thus determine the XiaoGouLi gold deposit is a magmatic hydrothermal type gold deposit related to the diorite porphyrite. |
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