| Because of its shallow location, large scale (most of them are large or super largemines), the epithermal gold deposit is highly valued with its important economicalsignificance. Dong'an gold mine that is a newly found has a larger potential andbelongs to the epithermal gold deposit with low sulfur.The area locates in the western continental rim of the yanshan-phase miningterrain of surrounding Pacific, also at the structure –magma acting terrain between theJiamusi-landblock and Songnen-landblock, in which the volcano-invasion wasintensive. The ore-forming is closely associated with the terrestrial phase sub-lavaespecially its space-time, matter-fountain, heat-source and shaping-forming.Controlled by the junior structure, that is NNW-NNE-NE orientation, of Kuerbincrust structure and cryptoexplosion breccia, the ore-beds coexist with the middlephase of yanshan alkali-lime granite vine . In this area 52 mine bodies, withlength ranging from 50m to 725m, thickness from 1.00m to 9.40m , the value of Au1.1119.83×10-6,Ag 1.0159.4×10-6 ,have been found ,among which the body 5 arethe main mine. One is 460m long, 234m vertical-depth, 6.70m thick, value of Au9.05×10-6,Ag 75.8×10-6, thickness changing coefficient is 75.3%, others (1-4, 6,10-14, 19) is 21.4-67.0%, mineral value changing coefficient Au is 380.9%, Ag is206.8%, others (1-4, 6, 10-14, 19) Au is 40.3-93.1%, Ag is 45.5-132.7%, Thestatistical results of mineral value and thickness show the mining is asymmetryand change maximum, other bodies, the value and the standard deviationof thickness are reversed. The alternation of the surrounding rock is intensive and its zonation isapparent. The inner tape is hydrothermal quartaite, adulariation and chloritization, themiddle tape is silication, net nervation silicon and chloritization and the hypo-outertape is pelitization(gaolinate, muscovite), outer tape is daolinate, sericite. The orebodies lies in the inner tape, which the forming temperature of mineral is low(200300℃), the salty degree of the mining fluid is low (48%),and themining depth is shallow(0.21.1km). The mining course can be divided into threestages, the early stage ivory quartz, the middle stage gray quarts-adularia,quarts-chlorite-sulfid, the last one net nervation. The mining was made mainly in themiddle stage and the Ru-Sr age of mineral is 108Ma. The distributing model of Auvalue is dual normal school with peaks, also shows the stages of mining.The sub-lava in the late period of middle phase of yanshan is main mining factor,which has Evolved from mantle – derived magma, remelts part of the crystalfloor, and belongs to the alkalescence series of calcium – alkalescence volcanorock, it correlates closely with the mining in both time and space , and there exists anapparent depending relation in the source of material and heat . At the interface ofupheaval and the sunk, structures here are highly developed and thereby providedanother important mining factor. The NNE Kuerbin structure brought themining under control, and it's NNW, NNE, NE directional junior structures becomethe ideal transporting corridor and gathering place of mine. In this area, thepre-Cambrian basement neutron -basis property volcano rock –fine clastic buildingand sub-Cambrian Xilin group in cap rock carbonatite –fine clastic building becamethe original layer of mining source. The invasion action was very intensive,including Caledonian , late indo-chinese epoch and the late phase of yanshan ,and the rock belongs to calcium – alkalescence volcano rock;the former providedpart of mining material , and as one of the surrounding rocks , the lattertwo provided the mining material and medium. The sub-lava in the late period ofmiddle phase of yanshan here didn't only offer a part of mining material, but alsoserved as a heat fountain. Based on the investigation to the areal geology conditionand the mine geological character, according to the theory of geological abnormitycausing mine and the theory of comparision, this article has made fully use of theresults of Geology, Physical exploration and Chemical exploration and have drawnout the 1:100001:2000 mining prediction in the area of Dong'an gold deposit and itsbackground, Two I-class districts and one II-class districts have been predicted. Thepredicted gold reserve is 5 tons.
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