Geological Characteristics And Metallogenic Prospect Of Damoqujia Gold Deposit In Longkou County, Shandong Province

Damoqujia gold deposit in Longkou county of Shandong province locates in eastpart of Yishu fault belt north part of Zhaoping gold ore-forming belt. Metallogeniczone is located in the famous Zhaoyuan-Laizhou gold belt in eastern, northern end ofLinglong gold field. Deposit produced in our country’s famous within the scope ofLinglong gold field, the tectonic location the circum-pacific metallogenic belt to go,northwest of north China platform glue uplift zone. Gold deposit outdoor layer aremainly archaeozoic Jiaodong suite, eastern outcropped Guojialing granite rock mass,the west is mainly large area development and Linglong gneissic granite. Fracturedevelopment in the studied area, strong magmatic activities, gold metallogenicconditions are favourable.In this article, through field investigation and indoor analysis and combiningprevious research results, analysis and summarizes the Damoqujia gold deposit inLongkou county of Shandong province geological characteristics and genesis,combined with the native rock geochemical survey results, analysis and evaluation ofprospecting perspective of the mineral, the main achievements are as follows:1. Damoqujia gold deposit by recruit-flat fracture section Jiuqu-Jiangjia mainfault zone and its upper and lower plate secondary fracture control. The mineralizationtype is a gold-bearing alteration type. The deposit experienced two metallogenicperiods (hydrothermal metallogeny and supergenic metallogeny) and fivemetallogenic stages. Hydrothermal mineralization can be divided into obvious Ⅰ pyrite-quartz vein; Ⅱ quartz-pyrite; Ⅲ quartz-polymetallic sulfide and Ⅳpyrite-carbonate4stages, including Ⅱ stage for gold enrichment of the main stage.The wall-rock alteration were mainly silicification，sericitization and pyritization.2. Molybdenite sample analysis results shows that the content of Re in the twosamples are1.42×10-4and1.10×10-4, so it can be speculated that Damoqujiamolybdenum mining area of ore-forming material sources may mainly mantle sourcetype. Molybdenite’s Re-Os Isotopic dating results shows that the two sample ofMolybdenite’s model ages are128.5±1.9Ma and131.1±1.8Ma, taking into accountthe form of molybdenite slightly earlier than the gold mineralization, it can bespeculated Damoqujia gold mineralization may be later than the gold mineralizationage128.5±1.9Ma.3. Damoqujia gold deposit in the four stages of quartz main development gasliquid two phase and three phase containing CO2two types of primary fluid inclusions,the inclusions mainly uniform temperature range is88.6℃~371℃, the salinity is0.53~17.19wt%NaCl. Fluid inclusions microthermometry test research shows thatthe early fluid mainly for medium temperature and low salinity NaCl-H2O-CO2system fluid, and had strong phase separation effect, the ore-forming fluid hasexperienced the initial immiscible, strongly and weakening of immiscible evolutionprocess.4. In the affected by the subduction of the Pacific plate under the environment oflithospheric thinning, Jiaodong region multiphase magmatism happened in Yanshanepoch, directly related to gold mineralization in this area for Guojialing granite dioriterock intrusion activities. Guojialing granodiorite in place, the influence of tectonicdeformation, tectonic magmatic differentiation fluid rich in ore-forming materialsweak precipitation and precipitation of gold element, the formation of gold deposit.So we think, in the diagenetic mineralization is mainly affected by circum-pacifictectonic domain. In combination with predecessors’ point of view and the study in thiswork Damoqujia gold deposit belongs to the medium temperature magmatichydrothermal type gold deposits, its formation and late Yanshan epoch Guojialinggranite rock diorite intrusion activities. 5. Element analysis, cluster analysis and factor analysis results show thatDamoqujia gold deposit borehole core and tunnel ore sample elements can be dividedinto three combinations: the As-Co-Sb-Au-Bi-Ni-Cu-Ag combination indicates theformation of gold associated with pyrite; Hg-Pb-Zn combination may represent thelead Pb-Zn stage mineralization; Mo poor correlation with other elements, whichindicates that no direct link with the gold mineralization. The polymetallic andmolybdenum mineralization stages, therefore, is only a small contribution of goldmineralization.6. Work based on the soil geochemical survey in the study area, the total orderelement anomaly of39, according to the associated elements and the result of clusteranalysis and combined with the conditions of element anomaly of sets and separatethree combination anomaly area. On this basis, according to the anomaly ofgeological features and geochemical anomalies, for301,295,294,295and291veinmineralization vision to carry on the preliminary evaluation, have shown goodmetallogenic prospects.7. Through the research of the geochemistry characteristics of mineral vein No.302and primary rocks，the authors proposed that the guide elements of front halo ofore-body were Hg-As-Sb， the guide elements of near ore or ore-body wereAu-Ag-Cu-Pb-Zn， and the guide elements of rear halo of ore-body wereBi-Co-Ni． Accordingly， the geochemical exploration model was established.Combined with76,80and84three main prospecting line section of the primary rockgeochemical survey work, put forward further prospecting mining area suggestion:302series is still mine focus, for further prospecting work in76,80and84threeexploration lines-600～-800m elevation range cloth hole prospecting.