| The Xianfengbeishan gold deposit in Heilongjiang province is located in thesouthwestern Wandashan massif, which is an important part of the Pacific metallogenic beltand belongs to Wandanshan-Sikhote Alin active belt. Wandashan massif is located in thenorth of Xingkai massif and the east of Jiamusi massif. The region mainly experienced theunderwent multi-period intense tecotonic and magamtic activities during the Indo-Chineseepoch and the Yanshanian, which provides favourable conditions for regionalmineralizaton. In this paper, based on a large number of geological data collection andsystem analysis about the prerequisite conditions of the region and mining area, throughfinishing the field geological investigation,sample tests and laboratoryanalysiscomprehensively of the Xianfengbeishan gold mining area, the paper mainlydiscusses the mining ore deposit geological characteristics, metallogenic phase partition,surrounding rock of mining area and mineralization era, deposit genesis and metallogenicgeological background.The Xianfengbeishan gold orebody mainly hostings in the acidic volcanic rocks inthe Pikeshan group,which controlled by EW fault zone.19orebodies has been found inthree mineralization and mostly show lenticular ore, Ores has the vein, stockwork veinletsdisseminated structure.the ore-forming process can be divided into three phase:agnetite-quartz,gold–quartz and Oxide phase. Wall rock alteration mainly hassilicification, sericite mudding, carbonation, propylitization，etc.Main metallogenic stage inclusions types mainly for gas liquid two phase, NaCl-H2Ofluid system of inclusions,the uniform temperature is range of105.5~277.8℃, the salinity is range of0.7~0.7wt%NaCIeqv, density is range of0.76~0.76g/cm3, ore-formingpressure is between8.92and19.30MPa, metallogenic depth is0.89~1.41km. It’s illustratethe main metallogenic stage fluid with low salinity, rich water, low temperature,metallogenic characteristics of low pressure, In summary,the Xianfengbeishan gold depositbelongs to hypabyssal hydrothermal type gold deposits with low temperature.The Xianfengbeishan gold deposit occurred in rhyolite, rhyolitic breccia and cuttingchip crystal tuff rock belongs to alkaline series, relative LREE enrichment, HREE relativelosses, light and heavy rare earth elements differentiation, has obvious negative europiumanomaly, enrichment of large ion lithophile elements (LILE), loss of high field strengthelements (HFSE), Rb and Sr, Ti and Zr, Nb and Ta ratio shows shell source characteristics.Mining area within granodiorite belongs to peraluminous high potassium calc alkaligranite type I, relative LREE enrichment, HREE relative losses, europium anomaly is notobvious, enrichment of large ion lithophile elements (LILE) Rb, Th, K, loss of high fieldstrength elements (HFSE) Nb, Ta, P, Ti, etc; Quartz diorite porphyrite with rich LREE,HREE relative losses, without europium anomaly; Enrichment of large ion lithophileelements (LILE) Rb, Th, K, such as loss of high field strength elements (HFSE) Nb, Ta, P,Ti and other geochemical characteristics show that it belongs to high standard aluminumpotassium calc-alkalic rock.Granodiorites zircon U-Pb age was128.3±2.6Ma, quartz diorite porphyrite zirconU-Pb age was108.48±0.99Ma, ore rhyolite and rhyolitic breccia zircon U-Pb agerespectively was116.98±0.47Ma and116.98±0.42Ma in the mining area, Bycombining on intrusive relationship of those rocks, Xianfengbeishan gold deposit formedin the late Early Cretaceous (116.98±0.47Ma and108.48Ma).According to the geochemical characteristics that wall rock and vein rocks show inthe mining area, basing the volcanic tectonic discrimination diagrams, In this paper, weconsider that the Xianfengbeishan gold deposit formed in the tectonic environment afterthe collision, diagenetic mineralization age, the formation of the Xianfengbeishan golddeposit closely relate with the sector split between jiamusi and wandashan massif causedby the subduction of the Pacific plate, which become a product formed in the ancient Pacific tectonic regime from Squeeze to stretch. |
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