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投稿时间：2018-08-06 修订日期：2019-04-20 网络发布日期：2019-07-03
Abstract:Located in the southwestern part of the Guyuan-Hongshanzi uranium metallogenic belt, the Zhangmajing uranium-molybdenum deposit is an important volcanics-related hydrothermal uranium deposit in China, whose uranium and molybdenum reserves all meet the standards of large deposits. Uranium orebodies are mainly distributed in the inner and outer contact zones of the rhyolite porphyry body. The distribution of molybdenum ore is slightly larger than that of uranium ore, but they are highly superimposed upon each other in space. A layer of mono-molybdenum mineralization is developed outside the uranium deposit, and the boundary obviously shows completely separate contact relationship. In order to explore the relationship between the uranium mineralization and molybdenum mineralization of the deposit, the authors analyzed the main trace elements of the uranium ore and molybdenum ore in Zhangmajing with Yb as the inactive component to calculate component migration quantitatively by Grant formula. Geochemical data show that the average content of uranium and molybdenum in uranium ore is 1589×10-6 and 3837×10-6, whereas the average content of uranium and molybdenum in molybdenum ore is 493×10-6 and 5706×10-6, indicating that molybdenum ore has higher Mo content and lower U content. The calculation results show that the isocon of uranium ore is less than 1 (0.48, 0.58, 0.46 and 0.53, respectively), showing that the components was brought in on the whole. The most obvious feature is that a large amount of SiO2 was brought in. Besides, ore-forming elements such as Mo, U, Zn, Cu, Ni, V, Pb and Co, alkali metals such as K2O, Na2O, Rb and Cs, and large ion lithophile elements such as Ba and Sr, were all brought in. The components such as Cd, Bi, Sc, and Eu also exhibit a large degree of being brought in, only a small amount of alkali metal of Li and MnO were taken out. The isocon of molybdenum ore is less than 1 (0.73, 0.67, 0.90 and 0.39, respectively), and the components were also brought in on the whole. The main elements were brought in, which included ore-forming elements such as Mo, U, Ni, Zn, V, Co, Cu and Pb, alkali metals such as K2O, Na2O, Rb and Li, and large ion lithophile elements such as Ba, Sr, TFeO, TFeO, Cd, Bi and Sc. Only Cr and MnO components were taken out. The Mo content of uranium and molybdenum ore increased to 7217×10-6 and 7759×10-6, respectively, indicating that the increased Mo was almost coincided. The U content of uranium and molybdenum ore increased to 3131×10-6 and 604×10-6, respectively, indicating that the increase of U in the former was much larger than that in the latter. Uranium elements and molybdenum elements show some similarities in the migration of the components in the standardized Isocon diagram, but the specific migration characteristics also show some differences. They show some similarity but are not identical. The authors hold that uranium and molybdenum orebodies were formed by different mineralization processes, as shown by the combination of the spatial distribution characteristics with their contact relationships. It is probable that the later rich uranium ore-forming fluid was superimposed on the early molybdenum ore.
keywords:geochemistry uranium metallogenic molybdenum metallogenic element quantitative analysis of component transfer Zhangmajing uranium-molybdenum deposit
SONG Kai,WU JianHua,GUO HengFei,GUO GuoLin.2019.Superimposed mineralization of Zhangmajing uranium-molybdenum deposit in northern Hebei Province: Constraints from mass balance migration calculation of ore geochemistry[J].Mineral Deposits38(3):599~619