Geological Features And Ore Prediction Of Yinchang Gold Deposit In Pingwu,Sichuan

The Yinchang gold deposit in Pingwu County of Sichuan Province,China is a medium-low temperature hydrothermal microfilm-disseminated gold deposit,it mainly controlled by fault and discovered in the 1990s.The deposit tectonically loacted in the northwestern margin of the Yangtze paraplatform,southwestern of Qinling Mountains fold system and southeast south of Western Songpan-Ganzi fold system end of three primary tectonic units of the transition zone.In this region,the main ore resource are found in the core of Jiaoziding brachyanticline and pre Sinian"Jiaoziding complex"and the southeast wing of the Cambrian Sinian strata,small medium and small gold deposit such as Yinchang,Hu Jiagou,jindonggou,Taoyuan gold deposit are found in this district.The regional faults and secondary faults like Huya fault and Qingchuan fault,snow-Maowen fault have close relationship with gold deposits there.The types of ore deposits are quartz vein type gold deposits and fine disseminated gold deposits.The ore bearing strata are Silurian,Devonian,Carboniferous and Triassic,the host rocks are mainly phyllonite,quartz vein,carbonaceous phyllite,slate,sandstone,fragmentation fragmentation recrystallization brecciola,recrystallization cataclastic limestone,foliated argillaceous limestone etc.The ore bodies in mining area are controlled by tectonical faults.The NW fault F₁ controlling the west ore bodies and the EW fault F₃₃ controlling the east ore bodies In the mining area exposed strata are mainly Carboniferous,Permian,Triassic and Quaternary,annd gold ore bodies are mainly exposed in Middle Triassic Zagunao group?T₂z¹?and the lower Carboniferous Xuebaoding group?C₁x?.Magmatic Iwade dew is not seen in the mining area,but the later vein body is extremely developed in the rich ore area and its near mine wall rock.The rocks in the mining area generally suffered metamorphism,alteration phenomenon is extremely developed,the main alteration are pyritization,cinnabar mineralization,arsenopyrite mineralization and limonitization.Ore minerals are mainly pyrite,cinnabar,arsenopyrite and orpiment,non metallic minerals are mainly quartz,feldspar,calcite and so on.Pyrite is the most common gold bearing mineral in the mining area.The samples of different elevation from top to bottom in gold orebody and analyzed the phase analysis of single minerals,that gold mainly in pyrite and arsenopyrite sulfide inclusion gold form,followed by Portland quartz inclusion gold form.Based on the quantitative calculation formula of Grigorian zoning sequence,the axial zoning sequence of the primary halo of ore deposits?from shallow to deep?is:Hg-F-Sb-Ag-As-Au-Ba-Cu-Ni-Zn-Co-Bi-S-Mn-B-Mo-W-Pb-Cd.These elements are basically consistent with the comprehensive axial zoning sequence of the primary halo of gold deposits in China,with front halo and ore nearing halo and tail halo intact.?Sb+Hg+F?/?W+Mo+Cd?"front halo/tail halo ratio changes regularly,suggesting that mineralization of gold deposits in the area are superimposed mineralization phenomenon,zoning index ratio of Ag/Au and the"front halo/tail halo"such as the ratio of?As+Sb+Hg+F?/?Mo+W+Pb+Cd?significantly increased in the middle district of deep area?1850m?,on behalf of 1800 meters is still the distribution of gold ore.The drilling work that shows the thickness of ore body and the grade become richer along the tendency,and the No.1 orebody in+1800m were not pointed out,indicating the promising extension of ore body deep down and there still has great metallogenic potential deep down.Study on the geological characteristics and ore controlling factors of Yinchang gold deposit,and combined with the axial zoning sequence of the primary halo of gold deposits,can effectively predict the potential resources of the deep edge of the deposits.In two main ore bearing strata?T₂z¹,C₁x?in the structural fracture zone,the possibility of the formation of gold deposits is very large;alteration phenomena such as pyrite,arsenopyrite mineralization and mineralization of cinnabar,limonitization concentrated development area also are prospecting area.The resources reserves under the control of Yinchang gold deposits have reached a large scale,and the prospective reserves have beyond large scale,with great potential potential and further exploration value.