Geological Characteristics And Genisis Of Zhengguang Gold Deposit In Heihe City,Heilongjiang Province

Zhengguang gold deposit located in Heihe city,Heilongjiang Province,the eastern section of Mongolia orogenic belt.By the end of 2009,the total mineral resources has been to 23 tons,which achieve the scale of large gold deposit,and the average grade of3.25 g/ton.Based on the geological characteristics and genesis of Zhengguang gold deposit,the article find out the deposit ore-forming physicochemical conditions and source of ore-forming materials,summarized the ore deposit genesis.The ore body is mainly distributed near the contact zone between the surrounding strata and diorite diorite veins,and the N E-oriented extension faults also partially controls the ore bodies.The hosted rocks of the ore bodies in the mining area mainly include volcanic tuffs,volcanic breccia and fine diorite in the Duobaoshan Formation.Among them,fine dioritic viens are formed in the Yanshanian(148±1 Ma),which is a series of sodic calc-alkaline rocks.The diorite are enriched in large ionlithosphile elements(Sr,Ba)and depleted in high field-strength element(Nb,Ta).They have no obovious between LREE and HREE,as well as slightly Eu anomalies.It was shown that the source of magma originated mainly from the upper mantle,and formed under the extensional extensional structure caused by the continuous subduction of the Pacific plate according to lithogeochemical constituents,the discrimination diagrams of Hf-Ta-Rba and MgO-CaO-FeOT.Metal minerals in ore mainly includ pyrite,chalcopyrite,galena,sphalerite,natural gold.Pyrite is the gold carrying mineral.The gangue minerals mainly include sericite,quartz,calcite,chlorite,epidote,etc.,showed the characteristics of low-temperature minerals as a whole.Hypidiomorphic granular texture is the main ore texture,followed by replacement of residual structure and emulsion droplet.Veinlet disseminated,brecciated structure are the main ore structure,followed by massive structure.Wall rock alteration types in the mine are propylitizationgreen and beresitization.The microscopic temperature analysis on fluid inclusions in quartz and calcite reveal that the metallogenic temperature of the gold deposit is between 125.8~286.4 and the main metallogenic temperature is between 130.2~226.1.The metallogenic fluid has the characteristics of low salinity(1.9%~10%)and low density(0.79~0.97g/cm~3).Main metallogenic stage pressure is low,from 10.46 to 10.46 Mpa main metallogenic stage metallogenic depth is between 1.05~1.96 km.S isotope test results show that the ore-forming material has the characteristics of mantle source.Deposit formation is closely related to late Jurassic magmatic activity.At this time of the extensional tectonic setting caused by the subduction of the Pacific plate.late Jurassic diorite offers metal ogenic material and heat sourceAbove all,Zhengguang Gold Deposit formed in the Late Jurassic,when the extensional tectonic setting caused by the subduction of the Pacific plate.And the mineral deposit genesis is.epithermal vein-type gold.