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Research On Geological And Geochemical Characteristics Of Porphyry Copper Deposits In Xinjiang Province

Posted on:2017-05-26Degree:MasterType:Thesis
Country:ChinaCandidate:M H XuFull Text:PDF
GTID:2180330482984071Subject:Mineralogy, petrology, ore deposits
Abstract/Summary:PDF Full Text Request
On the basis of previous research, in this study, we choose the Tuwu-Yandong porphyry deposit, Baogutu porphyry deposit, Qiongheba porphyry deposit, and Halasu porphyry deposit as the objects, and we focus on summarizing the features of diagenetic and metallogenic ages, geochemical characteristics of the ore-forming porphyry, geological characteristics and characteristics of the ore-forming fluids for the Xinjiang porphyry Cu deposits(Tuwu-Yandong, Baogutu, Qiongheba and Halasu).Meanwhile, we also have done some comparisons between the Xinjiang porphyry Cu deposits and the world typical porphyry Cu deposit(Dexing, Kounrad and Bingham).These results provide useful information to establish the regional metallogeny for Xinjiang porphyry Cu deposits. Our research offer scientific evidences for understanding of the regional metallogeny of porphyry Cu deposits and supporting for exploration of mineral resources in Xinjiang.Whole-rock major and trace elements data indicate that the ore-forming porphyries of Xinjiang porphyry Cu deposits display LILE and LREE enrichments and HREE and HFSE depletions. Sr-Nd-Hf isotope data indicate that they belong to adakite rocks, causing by the partial melting of subducted oceanic crust. Their tectonic settings are Subduction island arc environment.Diagenetic and metallogenic ages data indicate that Xinjiang porphyry Cu deposits occurred at the early Devonian, late Devonian, early Cretaceous and late Cretaceous. The Xinjiang porphyry Cu mineralization was mainly divided into two stages: the early porphyry Cu mineralization stage(412-377 Ma) and the late porphyry Cu mineralization stage(326-310 Ma).The Xinjiang porphyry Cu mineralization was distributed as disseminated,veinlet-disseminated and stock-work veins in the ore-forming porphyries, however the Cu mineralization was also occurred at the volcanic wall-rocks in the Tuwu-Yandong porphyry deposit. The alteration type and alteration zone of the Xinjiang porphyry Cu deposits are very similar. But, the alteration which was associated with the Cu mineralization was great different between Xinjiang porphyry Cu deposits.The ore-fluid features are totally different between Xinjiang porphyry Cu deposits(Tuwu-Yandong, Baogutu, Qiongheba and Halasu). Baogutu shows medium-high temperature with medium-high salinity, Tuwu-Yandong shows medium-low temperature with high salinity, and Qiongheba and Halasu shows medium-high temperature with(medium-) low salinity. Otherwise, The ore-fluids of Tuwu-Yandong, Baogutu and Qiongheba were derived from the magmatic water,while, the ore-fluids of Halasu was derived from the mixture between magmatic water and meteoric water.By comparisons between the Xinjiang porphyry Cu deposits and the world typical porphyry Cu deposit(Dexing, Kounrad and Bingham), we found that they have many similarities in geochemical features of ore-forming porphyry,mineralization and alteration characteristics. However, their ore-fluids features are totally different. The main difference is that the temperature and salinity of ore-fluids from the Xinjiang porphyry Cu deposits are distinctly lower than those of the world typical porphyry, which may be the vital factor for preventing the porphyry deposits in the Xinjiang to be the high grade world-class porphyry deposits.
Keywords/Search Tags:Xinjiang porphyry Cu deposit, Whole-rock geochemistry, magmatism and mineralization, porphyry alteration, Ore-fluid features
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