Geological Characteristics And Metallogenic Type Research Of Huaniushan Gold Deposit In Beishan Area Gansu Province

Beishan Orogen Central Asia orogenic belt southern edge, located in the two plates meet of the East Tianshan Mountains and the Tarim, the geological structure is extremely complex, regional stratigraphic complete development, both basic exposed. Area gold deposits are widely distributed, many types of deposit, metallogenic mechanism is complex. Overall, the Beishan orogenic belt gold deposits are mostly produced in the Paleozoic continental plate collision with docking, it has a certain spatial and temporal distribution. Huaniushan gold deposit is a typical gold deposit of Beishan Orogenic, this paper through detailed study of regional geological, deposit geology, geochemical and other aspects of Huaniushan gold deposit, the formation of the recognition:Huaniushan gold deposit occur in jixian system on third lithologic section marble and dark clouds felsic qualitative hornfels(original rock series argillaceous silty clastic rock) contact with parts of the calcium siliceous hornfels or in the skarn. Main orebody produced is symmetrical along the marble with dark clouds long the hornfels contact fractured zone between the layers. Have skarn ore rocks, marble, granite, long dark clouds the hornfels, quartz diopside Shi Jiaoyan, biotite cordierite hornfels, silicon card lithification marble, quartz of diopside Shi Jiaoyan as main mineralized rocks. The formation of ore deposits mainly experienced jet- sedimentary period, magmatic hydrothermal period(skarn stage, quartz-sulfide phase), supergene period.The formation of Huaniushan gold deposit and indo-chinese epoch- yanshanian intrusion is closely related to granite, mineralization is often produced in rock or the contact of a batholith. Through the rock geochemical characteristics show that the flower down gold mine of indo-chinese epoch, yanshan period is long should belong to the type I granites. Mother magma derived from the upper mantle- lower crustal anatexis, in the process of emplacement diagenetic assimilation, the contamination by upper crustal material. Ore-controlling factor analysis showed that the flower down gold mine is mainly controlled by strata, structure, magmatic activity. The magma activity have very important control action on deposit. Indosinian, yanshan epoch Rb- Sr isochron age of rock mass were 235.26±29.24 Ma and 220±4Ma,Skarn type gold deposits in the ore molybdenite Re-Os model age was 221.0 ±3.4 Ma, diagenesis and mineralization age nearly consistent.Huaniushan gold deposit content typomorphic characteristics of pyrite, according to most less than 2 S/Fe, proves the pyrite ore deposit belongs to the deficient sulfur type, conducive to the enrichment of gold. Co/Ni most between 1 ~ 5, the individual value of 15.167, in line with the magmatic hydrothermal genesis of pyrite, and at the same time shows that the ore-forming material characteristics of deep source. Au/Ag reached more than 2, reflecting the deposit for the high temperature magmatic hydrothermal origin. S/Se again take down gold in pyrite is magmatic hydrothermal origin. Fe/(S +As) between 0.499 ~ 0.513, shows deep source down gold in pyrite formation characteristics. To sum up, Huaniushan gold deposit belongs to medium high temperature magmatic hydrothermal genesis, metallogenic material source for deep source.Huaniushan gold deposit sulfide ore delta 34 s average of 0.57 ‰, has the characteristics of typical mantle source of sulfur, showed that the sulfur may take down gold from deep source, and Huaniushan gold deposit indo-chinese epoch, yanshan period is long granite intrusion mother magma from the upper mantle- lower crustal anatexis. To sum up, the ore-forming material is mantle-derived sulfur and evolved with remelted granite magma sulfur compounds. Fluid delta δ18OV-SMOW is 9.2‰~10.8‰, the delta δDV-SMOW for-116‰~-97.8‰, the ore-forming fluid delta δ18O H2 O is 3.9‰ ~ 5.5‰ of the delta, think the metallogenic fluid may be the product of magmatic water and atmospheric precipitation. The main metallogenic stage should be a temperature of 320℃~370℃, ore-forming fluid of high temperature, low salinity, rich CO2 and CH4 fluid.Huaniushan gold deposit after early jet may have the preliminary enrichment of gold, the main metallogenic period of magmatic hydrothermal activity not only brings together the gold basin sediments, and thermal contact metamorphism in the pyrite pyrrhotite, separation and enrichment again make native gold in pyrite. Think flowers down deposit genesis could spray flow deposits- magmatic hydrothermal superimposed transformation type compound genesis of gold deposits.