The Dachang gold deposit is located in the west of the north Bayan Har Orogen.The main orebearing strata is the Triassic Bayan Har Mountain Group,consisting of sandstone,siltite and carbonaceous slate.Orebodies are controlled strictly by the NW thrust faults,and commonly outcropped along NWW structural fracture in strips and lenses.They are characterized by wave-shaped bending and branchingcomplexing.In the plane,they are left-lateral right-step,however dextral left-step in the vertical,with a lateral trending of SE.Ore-related hydrothermal alteration is well developed and dominated by silicification,pyrite and arsenopyrite mineralization with a banded alteration zonation.The ore-forming process can be divided into four stages:barren mineralized quartz stage,gold-sulfide-quartz stage,gold-stibnite-quartz stage and quartz-carbonate stage.In addition,the results of soil geochemical survey for Au,As and Sb show the anomalies are obvious and have a prominent concentration center.The zonal anomalies are mainly coincident with the distribution of the orebodies.On the section,the peaks of content variation trend can also have a good correspondence to the orebodies.Combined with geological and soil geochemical characteristics of the Dachang gold deposit,the authors propose a prospecting model.According to the test,the model can provide the important reference in search of new orebodies for the prospecting work of the tectonic altered rock type gold deposit in Dachang,a national level equipped exploration district.
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