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Study On The Metallogenesis And Models In Mesozoic Epithermal Gold Deposits In Yanbian, Jilin Province

Posted on:2008-06-12Degree:DoctorType:Dissertation
Country:ChinaCandidate:H G ZhaoFull Text:PDF
GTID:1100360242960132Subject:Mineralogy, petrology, ore deposits
Abstract/Summary:PDF Full Text Request
Yanbian area is one of the most important gold-copper deposits concentrate province in east China continental margin ore-forming belts. It locates in the east of Xingan-Mongolia orogen,and controls by the North China Craton, Xingkai block and Jiamusi block. This area has experienced the Paleo-Asian Ocean evolvement, the subduction of plaeo-pafic plate to Paleo-Asian plate during Mesozoic, and these geological activities lead Yanbian district to be a continental margin multiple ore-forming area. Now days, A huge thermal gold-copper deposit, a tungsten deposit, and several epithermal gold deposits (Wufeng-Wuxingsan, Ciweigou, and Jiusangou) and three midthermal copper-gold deposit (Naozhi, Fuyan, and Duhuangliang) have been discovered and now under exploitation. Besides these deposits, there are a lot of mineralize occurrences. Theses evidences show that Yanbian area is a typical epithermal gold-copper metallogenic province. Former researchers have investigated the genesis and ore-forming models for these deposits, however, some questions still needed to answer: (1) the mineralization, alternation, and distribution character of these deposits, (2) ore-forming geochronology and related structure-tectonics,(3) properties of ore- forming fluid and its evolution mechanism, (4) mineral deposits investigation,exploration and resources forecast, (5) genesis of deposits and ore-forming model. On considering these listed questions, my study and research focus on the deposits geology, fluid characters, geochemistry, and geochronology, at the same time, the development of international studies of deposits were considered to construct the ore-forming model of this region.1 Regional Geological Setting and Ore-forming Dynamics of Yanbian AreaThis area has experienced a complex geological-tectonics history. The oldest strata are the early Palezoic Qinglongcun groups and Wudaogou groups. The late Palezoic strata are metavolcanic-metasedimentary rock series of Upper Carboniferous Shanxiuling formation, Permian Kedao formation, and Kaisantun formation. Tuntianying formation, Jingouliang formation, and Quanshuicun formation constitutes the Mesozoic strata. Cenozoic strata include Tertiary basalts and Quaternary sedimentary. Intrusive granites are formed in two stages, late Paleozoic diorite, granodiorite, and monzonite granite, and Mesozoic granite, granodiorite. Gold-copper mineralization thermal events are related with the Quanshuicun formation of basalt-andesite, andestie and porphyry andesite. The elements, isotopes geochemistry show that these the late Trias volcanic, hypabyssal rocks have the bimodal characters, which imply that there are two kind host magma. The basalt-andesite represents the primitive magma of basic ends while the rhyolite represents acidic host magma. The Sr-Nd isotopes have shown that the primitive magmas are generated from accretion crust materials located between the crust-mantle transition belts.2 Copper and gold deposits in the geological and geochemical characteristics of Yanbian AreaWe depth study of all sorts of copper and gold deposits and mineralized important point of deposit, Geochemical and fluid inclusions geological features in Yanbian Area.So confirm the large of the small southwest, Pingfu medium farmers Gold and Copper Deposits is disseminated thready-sulfide compound quartz veins. Naozhi copper-gold deposit, Copper-rich gold deposits is sulphide- quartz veins, Jiusan Ditch, Canglin and the groove Residents of copper-gold deposit are smaller veins disseminated. Duhuang Ling and the western slope of the copper-gold deposits are hidden breccia-sulphide complex quartz vein. Hedgehog gold deposit, Wufeng-five star mountain gold deposit contain sulfide quartz veins, calcite veins and ice feldspar quartz vein. And based on fluid inclusions homogenization temperature, salinity and stable isotopes, noble gas isotope research, we further educe: the large of the small southwest, Pingfu medium farmers Gold and Copper Deposits are High temperature oxidation of magmatic hydrothermal deposits,the ore-bearing fluid from the subduction of lithospheric mantle basement, secondary Boiling role of the fluid has created thready disseminated orebody, sulphides quartz veins of the Skyline Mine and Sulfide quartz vein, containing pyrrhotite veins brass, filling hydrothermal breccia orebody of the South Mountain Mina; Jiusan Ditch, DuhuangLing are high-temperature oxidation of magmatic hydrothermal copper- gold deposits or high-sulfide deposit;Naozhi and Copper-rich copper-gold deposit are Low Temperature Vulcanized copper-gold deposit; Hedgehog gold deposit, Wufeng-five star mountain gold deposit are typical low temperature and low sulphidation of the mainly atmospheric water hydrothermal gold deposit.3 The mineralization rule and mineralization model of Copper and gold of Yanbian AreaYanbian Area the distribution of rich gold-copper deposits, copper-gold deposit and gold deposits have obvious regularity.The rich gold-copper deposit locate in the eastern part of Yanbian uplift belt, High sulphidation copper-gold deposit located in Wangqing Mesozoic volcanic basin edge, Low sulphidation gold deposit locate in the five star Mountain-Wufeng and Wangqing Mesozoic volcanic basin, Low sulphidation copper-gold deposits locate in the west edge of Wangqing Mesozoic volcanic basin. Overall the two former locate in the eastern region of Yanbian, the two latter locate in the central part of Yanbian,Formate high magmatic hydrothermal oxidation of bronze of the eastern,copper-gold mineralization development, but the central is a low sulphidation gold, copper- gold mineralization development, and the magmatic arc background epithermal gold and porphyry deposit from Corbett(2002) ,the different of the conceptual model is the lack of typical porphyry copper deposit. Base on the Yanbian area of the copper-gold causes,Spatio-temporal distribution, establishment the suitable Deposit Mineralization model for the Yanbian region of high oxidation magmatic hydrothermal rich gole-copper deposits-magmatic hydrothermal high sulphidation copper-gold,low sulphidation copper-gold deposit-groundwater or atmospheric water-based low-sulfide gold deposits,and the various gold deposits within the heating source and oceanic plate subduction of the enriched mantle of the direct thermal power sources is the intrusion of granitic magma. The processes of Mineralization are the deposits of rich gold-copper is high oxide magmatic hydrothermal boiling by the secondary role of mineralization, copper-gold deposit is magmatic hydrothermal and atmospheric water or groundwater mixed with boiling role of mineralization, gold deposit is based on atmospheric water-based fluid crystallization precipitation mineralization.The innovation of this paper lies in the first put forward "Yanbian area of Mesozoic Endogenous copper-gold mineralization "were composite mineraliza- tion system of high high oxidation magmatic hydrothermal rich gold-copper deposits-high and low copper-gold sulfide-based magmatic hydrothermal, low- sulfide gold based groundwater or atmospheric water" . Identified the time of the Mineralization is between 123~102Ma. The study has important significance for guiding the area copper-gold exploration. This paper does not settle the question is that because a large numberof epithermal gold and porphyry deposits are closely associated, the intrinsic relationship between them are increasingly attracting the attention of deposits experts and the formation mechanism still needs further study.
Keywords/Search Tags:Yanbian Area, Mesozoic, Epithermal Hydrothermal copper-gold, Mineralization model
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