Evaluation On Gold Metallogenic Prospects To The North Of The Jiehe Gold Deposit, Zhaoyuan, Shandong Province

Jiehe Gold Deposit lays in the north of Wang'ershan fault of the Xincheng-Jiaojia fault zone in northwestern Jiaodong area,and it's in the north of Shangzhuang rock mass, which is constructed of Guojialing granodiorite. It is a gold deposit in the most north of the Jiaojia goldfield.Now seven orebody have been found and proved up in principal mining areas. There are also two ore prospecting spot in the periphery of mine field, Xiaolaowa and Xiaozhuangjia spot. The principal orebody has been mined down to -600m deep, the intensity of mineralization has obviously became weaken compared to the upper section, so it's important to prospect in the outer of the mine field. According to the model,the paper will evaluate on gold metallogenic prospects to the north of the Jiehe Gold Deposit in the way of the geology and geochemistry, have the deep-prediction of Xiaolaowa and Xiaozhuangjia spot, and fix on the prospecting targets.The strata don't develop in mining area, and its stratum is mainly the Quaternary stratum and the remained mass of Jiaodong group. The magmatic rocks include Linglong granite and Guojialing granodiorite. There are three northeast-direction ore- controlling faults in the area, they are Xincheng—Jiaojiafault,Houjia fault and Wang'ershan fault. Wang'ershan fault and its secondary faults control the orebody of Jiehe Gold Deposit. There are two series of fault tectonites: mylonite series and cataclasite series. The latter superposes and rebuilds the former, and forms compound fault tectonite.The seven orebodies in principal mining areas exist in the intense altered fracture zones of the top wall and footwall near the main fault plane in the Wang'ershan fault. The orebodies mostly present nervation, the prolongation of depth is often greater than that of the length. The ore includes several types, such as silicalite type,pyrite-sericite-quartz-type,potassic alteration cataclastic granite type,silicified cataclasite type,auriferous quartz vein type and auriferous quartz-polymetallic vein type. Ore have many typical hydrothermal fabrics. The wall rock alteration includes silicification,sericitization,pyritization,haematization,chloritization, carbonation, ferritization,kaolinization. The main mineralization period of the deposit is divided into four Metallogenic Stages: (I)quartz stage; (II)auriferous quartz-pytite stage; (III)auriferous polymetallic sulfide stage; (IV)quartz-carbonate stage. Jiehe gold deposit is low temperature hydrothermal deposit in genesis.The main ore-controlling factors are faults and magmatic rock in Jiehe Gold Deposit. The metallogenic regularity is important:①Orebody presents intumescence in the middle and shrunk in the tip .②The distribution of different orebody is about 200m horizontally far from each other,and it's almost equidistant.③The mineralization can be seen in the top wall and footwall along Wang'ershan fault belt.The main ore-prospecting geology symbols are listed as follows:①The ductility-friability superposing structural belt,the position where occurrence changes obviously,the interjunction of orbicular structure.②The contact zonebetween Guojialing granodiorite and Linglong granite.③The position where mafic-ultramafic dikes develop, especially such as lamprophyre vein.④The position where different kinds of alteration is superposed, especially the alteration going with intense sericitization,silicification and pyritization in a great deal of rubification (microcline) belt.⑤The position which have pyrite with different occurrence and little disseminated chalcopyrite,galena and blende.Xiaolaowa gold mineralization spot lies in the interjunction of huge orbicular structure, and its ore-controlling fault is inside the orbicular structure. Orebody is in the structural fracture zones of Linglong granite. Lamprophyre vein can be seen in the mineral vein. The ore type is mainly quartz-polymetallic sulfide and disseminated pyrite-sericite-quartz-altered cataclasite. The characteristics of mineralogy and alteration show that Xiaolaowa mineralization spot is hydrothermal deposit far from magmatic hydrotherm centre. Metallogenic depth is not very deep, and matallogenic temperature is low. In addition, the primary halo of bedrock in the mine well has the following characteristics. The space distributing regularity of elements conforms with the elementary normal vertical zoning regularity of hydrothermal deposit. From the top down, the supra-ore halo element reduces obviously, sub-ore halo element rises obviously, and orebody halo element greatly changes. These features show that mineralization range is not very large and changes great and rapidly, and metallogenic field may be not steady, so there's little possibility to form ore in the deep place.Xiaozhuangjia gold mineralization spot lies in the stable position of Wang'ershan fault. The secondary structure develops in the top wall and footwall. Ore-controlling faults become intense and broad, and approach the interjunctionespecially to southwest. The quantity of pyrite is not very much in the ore or metallogenic rocks, and mineralizing has something to do with chalcopyrite. The ore type is mainly quartz-polymetallic sulfide. The characteristics of structure and mineralization shows that this mineralization spot probably has the metallogenic prospect. From the geochemistry characteristics we can see that element groups is clear,element's vertical zoning is distinct, and the space distribution of elements indicates mineralization extend towards deep and gets better. The mineralization has the strengthening trend towards deep and southwest in the principal faulted structure, so it is important to pay attention to ore prospecting in the footwall. In the secondary structure,the mineralization also has the strengthening trend towards deep and probably becomes industrial orebody, the principal axes of mineralization enrichment pitch from northeast to southwest, and mineralization centre may appears below -450m.The paper derives several conclusion:⑴Jiehe gold deposit is a typical middle-deep veiny deposit, and the genesis of it is magmatic hydrotherm.⑵The ductility-friability superposing faulted structure controls the formation and distribution of gold deposit and orebody in mine field. The orbicular structure and the orbicular interjunction are both important gold mineralization position.⑶The mineralization type of Jiehe gold deposit is complicated. In the deep position, the mineralization type is mostly potassic-alterated cataclastic granite. In the principal faulted structure belt, it is pyrite-sericite-quartz-type, and it's quartz-pyrite vein type and quartz- polymetallic sulfide type in the secondary structure or in the shallow position.⑷There are three northeast-direction principal ore-controlling faults in thenorth of the Jiehe Gold Deposit, and they form a series of orbicular structure. Gold mineralization develops well in the strong structure stress position or construct interjunction.⑸There are some better mineralization prospective section in the north of the Jiehe Gold Deposit. They are the west of principal mine well,the north of principal mine well,Xiaozhuangjia,Xiaolaowa,Dingjiazhuangzi and Gaojiazhuangzi.⑹Two gold mineralization spot, Xiaolaowa and Xiaozhuangjia spot, both lie in the advantageous mineralized structural position, are both perfect prospecting targets.