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Mineralization Of Ductile Shear Belt Gold Deposit Of Bindaban In Xinjiang

Posted on:2006-12-07Degree:MasterType:Thesis
Country:ChinaCandidate:J S ShuFull Text:PDF
GTID:2120360182965213Subject:Structural geology
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Bindaban ductile shear zone is the main part of north edge of Middle Tianshan, at the same time it is the dominant metallogenic belt of Au and Cu. The classic gold deposits include Wangfeng gold deposit and Saridala gold deposit. Based on the former information and the new result of 1 : 50000 regional survey, the distribution and deformation feature of Bindaban ductile shear zone are found out in different scales. According to systematic research of the classic gold deposits' geology, structural geology and the geochemical characteristics ( stable isotopic ratio of C, H, O, S, Pb, REE and fluid inclusion), it discussed the ore-controlling mechanism ,the source of ore-forming materials and the feature of ore-forming fluid. Further more, summerized the metallogenic model of gold deposit in. Bindaban ductile shear zoneIt ascertains the distribution and scale of Bindaban ductile shear zone firstly, and summarizes the structure deformation characteristics systematically. The deformation inside the belt is characterized by strain concentration alternating with weak strain belt and strain transformation, The deformation fabrics are various, such as S-C> the tight homoclincal folding etc. Based on its deformation fabrics, kinematics and dynamic feature, the shear deformation can be divided into three phases: the shear deformation phase in early stage, the brittle -ductile shear deformation phase in mid-term and brittle deformation in later period.Bindaban ductile shear zone is the first class ore-controlling structure belt in this area, The gold deposits of Wangfeng and Saridala are rather similar, they are all the results of the evolution of Bindaban ductile shear zone. The brittle-ductile deformation transition controls the distribution of gold deposits strictly. To abtain following rules: (1) the brittle-ductile deformation transition can divided into strong-weak alternating type and original place transformation type, (2) the feature of strong-weak strain alternating and deformation transition in crosswise, longitudinal and vertical depth controls the distribution of deposits, it brings up the construction model of the brittle-ductile deformation transition space and gold deposit' distribution, (3) the brittle-ductile deformation transition belts are the collection belt of gold deposits, (4) gold mineralization lags ductile deformation, the main mineralization period is in brittle-ductile deformation stage.Suming up the reserach and comparison of C, H, O, S, Pb stable isotopic ratio and the REE in Wangfeng gold deposi and Saridala gold deposit, it manifests that the metallogenenic fluid of gold deposits is mainly metamorphic fluid, and sneaked into precipitate water later. The source of metallogenenic materials are metamorphic rocks of Changcheng system Xingxingxia group and S-type granite invaded during late Jialidong period. Some materials may came from deep crust or mantle.So metallogenenic materials has the multi-source feature.Depended on the testing of the temperature and pressure of Wangfeng gold deposit, its metallogenization homogeneous temperature is 151.2~434.5℃, and the primary metallogenization temperature is 331.2~228.2℃, secondary is 221.0~151.2℃. Contrasting with the decrepitation metallogenization temperature of Saridala gold deposit (170~410℃,the main is 270~300℃,and the secondary is 335~360℃;Wang Juli,1995), these show that the mineralization mainly occur on the stage of the medium-low temperature, and have the feature of the superimposed metallogenization.The research estimates the metallogenic pressure of Wangfeng gold depositfocuses on 22.13~40.83Mpa and 47.56~60.87Mpa, combining the achivement of the forefather's reseach synthetic, it reckons that the depth of the main mineralization period should not upward of 5.6km, when the crust was lifted up to about 2.0km, the mineralization is the most intense, the mineralization is basicly end when lifted up to about 1.0km. The research of Saridala gold deposit and Wangfeng gold deposit done by the forefather shows that component of the ore-forming fluid mainly consist of H2O and CO2, and less CO, CH4, H2, H2S. Depended on the temperature of the aqueous sotution inclusions of Wangfeng gold deposit, it estimate that the salinity of the H2O-NaCl system is 1.57-8.00%, the average is 3.786%, it is low salinity system. The fluid density of this system is 0.772~0.914g/cm3,the average is 0.847g/cm3.The single-grain Ziron age (SHRIMP) of the late-Caledonian mylonitization gramodiorite which is the wallrock of Wangfeng gold deposit is 432±5.6Ma. The magmatism certainly contributes the concentration of gold in late-Caledonian. The Geology and Rediometric data manifests that the terminating age of the ductile deformation should be before 302±6.2Ma, it is also before late-Carboniferous. The gold mineralization formed in the stage of the brittle-ductile deformation following the ductile deformation, belongs to late-Variiscan. At last, it summarized the metallogenic model of gold deposit. In the Bindaban ductile shear belt.
Keywords/Search Tags:Bindaban ductile shear belt, gold deposit, brittle-ductile deformation transition, minaralization, metallogenic model
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