The Study On Ore Deposit Geological Features And Regularity Of Donggou Gold Deposit In Fengning, Northern Hebei Province

The Donggou gold deposit in north Hebei province is located at the middlesection of the northern margin of the North China Craton, which is one important goldand polymetallic metallogenic belt in china. It has undergone long-term andcomplicated geological structure evolution, and possessed a gold ore-forming tectonicand geological background. Based on the results form from previous studies，wesummarized the regional metallogenic background of Donggou gold deposit. Besides,Moreover, by integrating the summarized data with field geological investigation, aswell as comprehensive indoor research，we completed a relatively systematic research,such as the geological characteristics, types of alteration and mineralization, structuresof the fault, characteristics of ore-forming fluid, geochemical characteristics of REEs.On the basis of the comprehensive research on strata, sturcture, magmatic rocks andvein rock of the gold deposit，we can summarize the metallogenic regular and providethe theoretical basis for the further ore prospecting. The major points are described asfollows：1. The Donggou Gold Deposit mainly consists of altered rocks and quartz veins.The mineralized zone and ore-bodies are strictly dominated by rift，and exist in thenear SN structure-alteration zone, with shapes of lentoid and veined. Mineralization iswidely correlated to silicification and beresitization. The major carrier of gold arefinegranular and farinose pyrite.2. The wall rock alteration of the Donggou gold deposit has a horizontal zonation.With the lode-potassic alteration in the center, follow by beresitization-cataclastite-potassic alteration and phyllic cataclastite-potassic alteration granodiorite.3. The deposit was formed in the hydrothermal period, which consists of threemineralization stages, including quartz-pyrite stage, quartz-polymetallic sulfide stageand carbonation stage. Therein, Quartz-polymetallic sulfide stage was the mainmineralization stage.4. The researches of fluid inclusion show that the density and salinity ofore-forming fluid are0.75~0.88g/cm3and3.90~9.18%respectively, the majormineralization temperature varies from265to315°C, the pressure and depth can bedetermined as21.5to30.5Mpa and1.2to3.8km respectively through calculation.Donggou Gold Deposit is a middle-low salinity, low-density, middle-shallow and mesothermal deposit.5. REE characteristics of Donggou Gold Deposit show that the substance ofdiagenesis and mineralization are congenetic and inherited. Shantazi Group is the only“Source Bed”of gold in deposit are. Gold was extracted from Shantazi Group firstby the magma activity of remelted granitoids in late Hercynian, and then enriched inpost-magmatic hydrotherm, resulting in the formation of the deposit along the NE andNS fault structures.