| Yangshan gold deposit in west qinling mountain belt in South Asia, for the important gold metallogenic belt in China. In this paper, on the basis of field geological investigation and laboratory analysis test, by lithology, rock geochemistry, fluid inclusion study, obtained the following results:1, Granite rock in the Yangshan gold deposit has the SiO2content of70.41%～74.89%, average72.00%; TiO2average content0.24%; A12O3average content is15.13%; CaO average content is1.61%; Alk (Na2O+K2O) content is2.39%～6.78%, average3.70%, including Na2O content of0.11%～3.95%, average0.63%, K2O2.25%～3.92%, average3.07%; A/CNK:1.142.74with average of2.03, could be assign to peraluminous. The trace elements generally show Ba、P、Nb、S、Ti losse, and Rb、K、La、Nb、Hf、Tb rich. The total igneous rock REE content is higher he studied area and less volatility (∑REE57.2-90.9×10-6, average82.97×10-6). LREE rich and (La/Yb) N8.92～24.51. REE shows different degree of fractionation, LREE and HREE also appears certain degree of fractionation; Showing relatively medium negative Eu (Eu/Eu*=0.66-0.90, average of0.79), which indicates plagioclase has a certain degree crystallization or left from the source rock during the magmatism process. The rock belongs to high potassium calcic-alkline series, due to the crust material partially melting and formed in orogenic environment.2, granite LA-ICP-MS zircon U-Pb age research results show that:1) granite porphyry zircon age spectrum of new archean to the Jurassic;2) inclined long granite porphyry zircon ages from paleoproterozoic to cretaceous spectrum;3) altered granitic aplite zircon age from the proterozoic to the characteristics of the pedigree of the silurian. Combined with regional geological features and granite type of intrusion in the devonian system in the study area can be deduced that yangshan area phase exist indosinian and yanshan period two granite rocks, granite porphyry formed in the Jurassic (J), plagioclase granite porphyry formed in the cretaceous (K), and the indo-chinese epoch before the zircon is granitic magma formation and intrusion process captured crystalline basement and the palaeozoic fold basement of zircon, indicating existence before the Cambrian in the area of crystalline basement. 3, fluid inclusions in the growth medium, simple type, mostly rich liquid inclusions (L V), a small amount of pure liquid (L), the composition of inclusions are mainly CO2, carbon-water system, and a small amount of CO. Host minerals mainly quartz. Fluid inclusions in quartz randomly scattered distribution, sections of the collection. Fluid inclusions, uniform temperature in the low temperature area, there are two peaks, and salinity. Results also show that different salinity of fluid mixing, temperature changes in temperature and pressure and cooling, the change of dilution and PH and EH value, is an important factor in mineral precipitation occurs. Source of ore-forming fluid mainly for tianshui, have joined from magmatic hydrothermal constituents, concluded that yangshan gold deep prospecting prospect is larger. |
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