Study On The Geological Characteristics And Prospecting Direction Of Juntun Gold Deposit In Qian'an City Of Hebei Province

Juntun gold mine is located in Jianchangying town of Qian'an,Hebei,which extends from Juntun to the north of Sanjia village.It is a proven medium gold deposit.When it comes to tectonics,it is located on the southern margin of the Lengkou basin(Lengkou fault and Qinglong-Luanxian fault intersection)of remnant detachment layer of mantle branch structure in Jidong-Jurassic upper permian basin mineralization subzone.Mineralization is mainly controlled by faults within the Lengkou basin.Based on the data collected by predecessors,we obtained mass of first-hand data from outdoor survey of geology,the collection of rock and mineral samples and the analysis of fold,fracture,isotope and inclusions in this area.Moreover,based on the theory of mantle branch structure,the metallogenic regularities and ore-controlling factors are analyzed.Meanwhile,the association between tectonic-magmatic-metallogenetic evolution in Jianchangying area is studied synthetically.Combined with geophysical and geochemical data,the prospecting potential of this area is analyzed to find favorable metallogenic area.Through comprehensive analysis of the Juntun gold deposit,the following understandings are achieved.1)Juntun gold deposit is located in the Jidong mantle structure of the outer part of the cap rock and the basement magmatic metamorphic complex between the dominan detachment-slip zone of the upper part of the plate with residual rock,ore deposit for Gaoyuzhuang Formation of Changcheng Department and Yangzhuang Formation of Jixian Department.Lengkou fault structure controls the ore guiding,and the magmatic activity communicates with the deep ore source.2)The ore bodies generally extend in parallel arrangement in northwest direction.the mineralization types are mainly shallow breccia type,deep altered dolomite type and vein rock type,and the mineralization is close to the wall rock alteration to carbonate,pyrite mineralization,limonitization,iron dolomitization,mudification.3)The source of ore-forming material is closely related to the regional Yanshan magmatic activity.The isotopic analysis indicates that the ore-forming materials are mainly from the deep of the earth.The ore-forming fluids are mainly magmatic water with a little metamorphic water and precipitation.The mineralization period is early Yanshan.4)Through the study of mantle structure theory,Juntun gold deposit is the process of mantle branch formation in Jidong area.The basement metamorphic rock strata are uplifted,and the overlying strata are separated and slipped.In the detachment slippage process by reverse shovel-like Lengkou fault block,and some overlying strata remain.The ore-bearing hydrothermal fluids along the dominan detachment-slip zone and the Lengkou fault to the structural weak belt metallogenesis.Combined with the geological characteristics of this area,we suggest some importances should be paid more attention,such as the dominant and secondary detachment-slip zones of the mantle branch structure,fracture alteration zone and deep ore prospecting.