Analysis Of The Genesis And Estimation To The Reserves Of Sandaowanzi Gold Deposit In Heihe County, Heilongjiang Province

The Sandaowanzi rock gold deposit is located in Sandaowanzi Village, Heihe City,Heilongjiang Province, in the northeast part of the Ordovician Duobaoshan island-arcactive belt within the early Paleozoic Daxinganling continental marginal accretional belt.Main intrusive rocks in mining area is pre-mineralization adamellite and littlepost-mineralization diabase-prophyrite vein, rhyolite porphyry vein. The strata exposed inthe mine area are the upper Jurassic Tamulangou Formation and the lower CretaceousGuanghua Formation. The structure in mining area is dominated by NW-striked ones. Thegold-bearing quartz vein exists in NW structure fracture zones cuting TamulangouFormation. The NE-striked structure occurs after mineralization. By previous research,three mineralization belts and42orebody （included21blind orebody） are delineated.According to gold ore grade, they are divided into low grade orebody (1.0×10^-63.0×10^-6),industrial grade orebody (Au≥3.0×10^-664.0×10^-6), industry grade ore shoot(Au≥64.0×10^-6). The main ore types in Sandaowanzi gold deposit consist of quartz veinand silicatization trachy-andesite ones.The main metallic minerals are Au, Ag telluridesand sulfides. Au has closely relationship with sulfides and tellurides. Tellurides includescalaverite, sylvanite, krennerite, petzite, hessite, empressite. Sulfides includes pyrite,chalcopyrite, galena, sphalerite and so on. Based on previous researches on petrographyand mineralography, we systematically identified lithology and altered types ofsurrounding rock. Simultaneously, we identified main ore types and texture. It wasconcluded that ore textures include euhedral granular texture, anhedral granular texture,replacement texture, poikilitic texture and cataclastic texture. Previous research indicates that ore-forming fluid is characterized by low salinity, low temperature and hypabyssaldepth. By isotopic studying, gold-bearing quartz grains have δ¹⁸OV-SMOWvalues rangingfrom-2.9to-0.2‰and the δDV-SMOWrange from-110to-185‰. And the calculatedδ¹⁸O‰of water range from-15.3to-9.9‰. These values show that the ore-forming fluidis mainly derived from meteoritic water. Previous research indicates that the δ³⁴S valuefrom Sandaowanzi gold deposit varies in the range of-1.1¹.7‰. The range is relativelynarrow and close to the sulfur isotopic composition of meteorite, so it was concluded thatthe sulfur of gold deposit comes from deep magmatic source. By the previous research ofPb isotope, it was considered that the Pb isotopic compositions between gold-bearingquartz vein and wall rock have little difference. And their lead source for ores is inaccordance with those of wall rock. It was concluded the metallogenic material derives notonly from magma, but also from volcanic sequence.In short, after synthetically research on mineralization background, geochemicalcharacteristics and fluid inclusion for the Sandaowanzi gold deposit, it was summarizedthat the deposit belongs to the epithermal deposit, which is related with magmatic activityduring the late Yanshan hydrothermal activities. Its Au abundance has relatively obviouspositive correlation with those of Te, Ag. We make it sure that Sandaowanzi gold depositbelongs to associated type gold deposit. Finally, by the means of geologic block method,we estimate Au, Ag and Te resource for the Sandaowanzi deposit as follows: the goldreserves reach to16143.63kg, including243.54kgⅠ₂F₁gold ore shoot,9580.53kgⅠ₂F₂gold ore shoot,5470.30kg industrial gold ore-bodiesⅠ₂+Ⅰ₃,849.26kg industrial gradeore bodies Ⅲ₁+Ⅲ₂-2. The silver reserves reach to68111.05kg, including35284.75kgsilver rich ore body Ⅰ₂F₂,32826.30kg industrial grade ore bodiesⅠ₂+Ⅰ₃+Ⅲ₁+Ⅲ₂-2.Tellurium reserves are up to21850.78kg.