Geology-Geochemical Features And Metallogenic Prognosis In Jiehe Gold Deposit, Zhaoyuan City, ShanDong Province

Jiehe gold deposit is located in Jiaojia gold ore-field,Zhaolai fault zone, which belongs to northwest of Jiaobei Terrane.Regional strata mainly consist of Archaean Jiaodong group, early Proterozoic Fenzishan and Jingshan groups,middle to late Proterozoic Penglai group. Early ore-controlling structure can be represented by the E-W extending Xixia superimposed anticline in this area,whereas a series of NE-striking fractures are developed as the later ones.The exposed magmatic rocks can be classified into Linglong gneissoid granites,Guojialing porphyritoid granodiorite and Luanjiahe medium-corse-graned granites. The paper firstly presented geological features,mineralization law and ore-controlling conditions of Jiehe gold deposit by combining of previous researches and our geological achievements,with discussion of ore formation nature.It is suggested that mineralization type in Jiehe gold deposit and its prospecting district is typical hydrothermal genesis,with midium ore-forming tempera-ture,taking intrusions and fault structures as its major ore-controlling fac-tors.Moreover,ore-forming fluid is the mixture of magmatic fluid and circulated meteoric water On the basis of discussion in previous section, basic geology and mineralization charactoristics are figured out and potential mineralizing districts are evaluated.Stratas in studing area are relatively simple,mainly Quaternary materials and Jiaodong group which remained as relicts found in Linglong and Guojialing intrusions. It is showed that general features in prospecting area are sulfide-rich,such as chalcopyrite,galena, sphalerite etc and depleting in pyrite. Mineralization types can be classified into two tyes, alterated type and fractured(cracked) type.Similar to other parts of Jiaojia ore-field,wall-rock alterations here are mostly silicificaion,sericitization, pyrition,chloritization,carbonatization ect.According to previous studies,there are mainly three sub-faults in this area ,It showed some differ-ent characteristics as correllating to other parts of Wangershan fault zone,the features can be concluded as followings:single fractures widen from southwest to northeast,widths between structures become smaller.In the study of traditional geology mapping,three ore-controlling fractures,five lenticular structures,eight converge positions are proposed.Three mainly controlling structures are:â‘ Xichenjia-Zhusong-Xiaolaowa-Xinzhuang fault(wangershan fault);â‘¡Haibu-Xiaozhuangjia-gaojiazhuangzi fault(xujiatan fault);â‘¢Haibu-dingjiazhuangzi-cikou-zhusong fault.Five major lenticular structures are:â‘ zhusong-gaojiazhuangzi lenticular structure (significant);â‘¡dingjiazhuangzi-gaojiazhuangzi lenticular structure (significant);â‘¢haibu-dingjiazhuangzi lenticular structure;â‘£xiliang-xiaozhuangjia lenticular structure;shangzhuang-xichenjia lenticular structure .Eight significant converge positons are:gaoiazhuangzi,xiaolaowa,zhusong,north and west of major hole,east of dingjiazhuangzi,dingjiazhuangzi,haibu. A detailed study of secondary halo in soil is carried out,emphasizing its features and a varity of information for forcasting of ore bodies orientation are put forward. It is significant to calculate the element background aboundance and the its upper limit,which firstly established in the course of geochemical data analysis, serving for delineating geochemical anomals.Four methods are proposed, establishing seven Au anomalys in proper order, according to elements assemblage features.The smaller the figure is,the more prospecting it is expected.Meanwhile factor analysis and correlate analysis imply the distribution law as well as assemblage feature of element Au,Ag,As,Sb,Bi,Hg,Cu,Pb,Zn,Co,Ni,Mo.Study on simple element anomaly of geochemical primary halo indicates that Au1 and Au6 probably have more potential minerlizational capacities exculded those difficult to have samples.Methods of comprehensive index and corresponding analysis are applied during assemblage analysis.Measurement of mercury in soil,as suplementary ways,gave another order of previous seven Au anomals.Finally,a sequence of Au anomalys is established with regards of prospecting capacity according to all of above methods.The major results are presented as follows:1.Ore-controlling structures are mainly composed of pressing ring structures,whose convergent points are the most favoribal mineralization zones;ore-controlling faults are distinct from other parts of the ore-field by developed fractures. 2.Wall-rock alterations are mostly chloritization and epidotization,which developed widely,not restricted arround or in the fault zones.Siliconization and sericitization are relatively weaker as well as potassization.3.Mineralization are major quarz-chalcopyrite,whereas pyrite is de-pleted,galena and sphelerite are relitively enriched but bearing poor-gold;mineralization types are complex,generally potassic granotoids type in deep level,pyrite-sericite type in major fault zones,whereas quarz-pyrite lode type and quarz-multi metals sulfidation type in shallow or medium level of sub-faults.4.By combining of previous researches and our geological achieve-ments,with discussion of ore formation nature,it is suggested that mineralization type in Jiehe gold deposit and its prospecting district is of typical hydrothermal genesis,with midium mineraliaton temperature,taking intrusion and fault structure as its major ore-controlling factors.Moreover,ore-forming fluid is the mixture of magmatic fluid and circulated meteoric water...