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基于显微薄片观察、稀土和微量元素分析探讨了鄂尔多斯盆地北部东胜地区中侏罗统直罗组砂岩的物源和铀矿化的地球化学特征。砂岩样品含有多种的变质岩岩屑应来自盆地北部的变质岩,那里的花岗片麻岩和斜长角闪岩分析显示:花岗片麻岩LREE/HREE为19.02,斜长角闪岩LREE/HREE为4.47。这两类母岩LREE/HREE比值分别接近于砂岩最高和最低LREE/HREE比值,其稀土配分曲线模式与砂岩LREE/HREE比值端元岩样可以对比,说明砂岩的母岩主要来自这两类变质岩。花岗片麻岩Th/U高,表明发生铀丢失,可作为本区铀成矿的重要铀源。有意义的是,铀含量高的样品,其LREE/HREE比值高,铀含量与亲硫的微量元素Pb、Zn和Mo具有相关关系,这些特征可作为铀矿化的重要标志。
Based on the observation of thin sections and analysis of rare earths and trace elements, the geochemical characteristics of the source rocks and the uranium mineralization of sandstones in the Zhiluo Formation in the Dongsheng area, northern Ordos Basin, are discussed. Sandstone samples contain a variety of metamorphic rock cuttings from the metamorphic rocks in the northern part of the basin where the granitic gneiss and amphibolite show that the LREE / HREE granitic gneiss is 19.02, amphibolite LREE / HREE is 4.47. The LREE / HREE ratios of these two types of parent rocks are respectively close to the highest and lowest LREE / HREE ratio of sandstone. The patterns of rare earth distribution curves can be compared with those of LREE / HREE ratio of sandstone, indicating that the parent rocks of sandstone are mainly from these two types of metamorphism rock. Granite gneiss Th / U high, indicating the occurrence of uranium loss, uranium mineralization can be used as an important uranium source. Significantly, samples with high uranium content have a high LREE / HREE ratio. Uranium content correlates with the pro-sulfur trace elements Pb, Zn and Mo, and these characteristics can be used as an important indicator of uranium mineralization.