| The Ordos basin is an important energy and mineral resources base in our country, and a typical basin that organic and inorganic energy mineral is coexistence and enriched. In recent years, the Dongsheng and Hangjinqi sand-type uranium deposit is discovered in the north of basin that let more scientists to focus on this area. The present study suggests that since the meso-cenozoic, there is strong reformation in the basin, that lead to the damage and reconstruction of the reservoir, and the oil and gas migration to the north of the basin, and the generated after rock alteration and uranium deposits in the study area location. On the basis of existing research results, combined with the feature of newly discovered an adapted uranium deposit in recent years, mainly from the perspective of stable isotopes in the region after the formation rock alteration and uranium enrichment and hydrocarbon dissipation is studied to explore its relationship.For distribution of the bleached sandstone, the green alteration sandstone, the carbonation and pyritization of ore-bearing bed in the study area, with the widely used in the study of tracer of C, O, S, H and Si of stable isotope composition, we will study the series of digenetic alteration phenomenon. The study found that pyrite sulfur isotope and the characteristics show the characteristics of organic origin and biological function, that reflect widespread microbial action, through comparing the sulfur isotope, it mainly comes from the upper paleozoic gas dissipation effect, and a few from the formation of cinder and Yanan formation of strata under the coal seam of hydrocarbon generation. Carbonate rock in the aggregate and cement epigenetic C-O isotopic compositions, which show the characteristics of organic carbon, and at the same time, the formation of carbonate lithification effect and gas dissipation function, upper Paleozoic and microbial activities related late. At the same time, contrast genesis of silicon isotope composition of kaolinite and uranium found that both have highly consistency, that proved there are both genetic and physical contact, further proved that the formation of kaolinite and late uranium enrichment is controlled by regional hydrocarbon dissipation function. Uniform temperature tests have shown that there are different properties of multiphase fluid flow, including early normal temperature fluid (45℃～65℃) represents the fluid characteristics of interlayer oxidation zone formation, late also has low temperature hydrothermal fluid activity (14℃～180℃), the period represents the gas dissipation under the action of fluid properties of low temperature hydrothermal fluid; H. O isotopes of Inclusion shows that the water in ore-forming fluid is given priority to with atmospheric precipitation, at the same time by gas contamination in hydrogen isotopes. Comprehensive comparing metallogenic time, oil and gas filling time and basin hydrothermal activity time, found that they are coupled to each other in time, the previous research thought for the relations between and among the above provides evidence of stable isotopic composition.All evidence reflects that the formation of Hangjinqi-Dongsheng uranium metallogenic belt and the phenomenon of diagenetic alteration is controlled by the regional hydrocarbon dissipation function. Under the background of basin stage of tectonic evolution, coal-derived gas in Upper Palaeozoic dissipate to the northern of basin along the tectonic belt, meanwhile the deep fluid mixed with it and heated it up. The low temperature alkaline hydrothermal fluid passed Zhiluo and Yanan formation to react with uranium, and lead to the diagenetic alteration and mineralization, eventually formed the all-in-one Uranium ore concentration area. |
PDF Full Text Request