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Study On The Characteristics Of Ore-forming Fluid And The Genesis Of Porphyry Copper Deposit At Muji Village

Posted on:2012-03-01Degree:MasterType:Thesis
Country:ChinaCandidate:M GaoFull Text:PDF
GTID:2250330401977440Subject:Mineralogy, petrology, ore deposits
Abstract/Summary:PDF Full Text Request
The copper deposit of Muji Village is located in Laiyuan county of Hebei province. Themain rock is part of the Laiyuan complex or as so called Wanganzhen complex. The orefieldis controlled by deep fault and Mesozoic fault basin. Wulonggou-Shanghuangqi fault existedfor a long time, and had several movements. It controls the deposit, and formed thecharacteristics of this area, and the orefield lays in it.In this article,the Geological background,characteristics of the deposit,mineralizationzones,types of rocks and its distribution are observed and analyzed, especially the fluidinclusion in the quartz veins, in order to find the relationship between the fluid and themagma, so we can discuss the role which the fluid play in the ore forming process. Weacquired the homogenization temperature of114.9~471.6℃, and there are two peak value at200℃and400℃, we can see that it has two steps to form the deposit. While the salinity hastwo peak value at9%and20%, indicates the fluid is low salinity fluid.The isotope data performs a deep source characteristics, and the water in the inclusion isnot exactly the magma water, but the water in the skarn type minerals of the outer zone isclose to magma water, as the ore forming process goes, the rain component increases. Thealteration types of the wall rock in this area are mainly porphyry hydrothermal type, there arepotassic alteration, silicification, Propylite alteration and argillic alteration,the potassicalteration and silicification are related to copper mineralization especially the potassicalteration. There are two types of ore, porphyry and skarn, indicates that there are more thantwo kinds of the mineralizations.By analyzing these data and the information, we discussed the forming mechanism of theore deposit. At Mesozoic Era, the mantle magma went up to the lower earth crust, and causedpartial melting,formed adakite magma. Meanwhile, in the high oxygen fugacity,chalcophileelement went into the residual magma as incompatible elements,the residual magma becamethe ore forming fluid. During the Yanshan movement, the magma chamber keep injectingfluid up to the dioritic porphyrite and its wall rocks,the strong alteration formed the porphyrycopper(molybdenum) deposit. The temperature and the salinity decreased as the mineraldeposition and the injection of the rain water. There is also a second alteration to the dioriticporphyrite and the wall rock, and the contact metasomatism made the ore body and the wallrock secondarily mineralized and alternated into a skarn ore deposit.
Keywords/Search Tags:Muji Village, copper deposit, fluid inclusion, ore forming fluid, formingmechanism
PDF Full Text Request
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