鄂尔多斯盆地北部直罗组有机质特征及与铀成矿关系

The Organic Matter Characteristics of the Zhiluo Formation and Its Relationship With Uranium Mineralization in the North Ordos Basin

本文研究了鄂尔多斯盆地典型铀矿床的有机质与铀成矿的关系。探讨了煤屑的赋存状态、煤质特征及成熟度,认为煤屑的演化程度均较低,处于低成熟阶段,有利于对铀的吸附。总体上看煤质有机质和铀矿化关系密切,铀含量与煤屑含量呈正相关关系,对铀矿物为吸附态形式。通过对该区油气包裹体的研究认为,该区存在多期次的成岩方解石胶结过程,并伴随多期次的油气包裹体发育,尤以晚期的胶结方解石矿物中存在丰富的晚期油气包裹体。研究认为晚期可能发生过油、气的运移和聚集,铀矿床的形成与赋矿砂岩中有机流体或还原性气体的充注和络合作用密切相关,因而这些丰富的有机流体和还原性气体对于铀的富集沉淀具有重要意义。

With the focus on the relationship between the organic matter and uranium minerlization of typical uranium deposits in the Ordos Basin, this study discussed the occurrence, characteristics and maturity of the coal. The results show that the evolution degree of organic matter is low and still in the low stage of mature, indicating it is favorable to the adsoption of uranium. Overall, organic matter in coal is closely related to the uranium mineralization, and positive correlation between the contents of uranium and organic matter coal suggest their adsorption form. The study of oil-gas inclusions in this region indicates occurrence of multiple calcite cemetation, along with multiple development of oil-gas inclusions, especially abudant late-stage oil-gas inclusions in late cementation calcite minerals. It can be concluded that it could have the migration and accumulation of oil and gas in this time, and the formation of uranium deposits is closely related to the filling and complexation of organic fluid or reducing gas in ore-bearing sandstone. Therefore, the organic-rich fluid and reducing gases are of great importance for the uranium enrichment and precipitation.