砂岩型铀矿的双重还原介质模型及其联合控矿机理:兼论大营和钱家店铀矿床

含铀岩系的还原介质可以依据与铀储层砂体的产出关系划分为内部还原介质和外部还原介质.铀储层砂体的双重还原介质对铀成矿同等重要.铀储层砂体中的层间氧化作用直接与内部还原介质相关，但是当叠加有外部还原介质时，外部还原介质将通过不同的方式大大增强铀储层砂体的整体还原能力，这种组合的出现有利于稳定的层间氧化带发育和持续的铀成矿.沉积期的古气候和沉积环境决定了含铀岩系还原介质的类型和丰度，以及铀储层砂体双重还原介质的组合规律，并从根本上决定了成矿期层间氧化带的发育规模.在进行砂岩型铀矿的勘查预测时，需要将双重还原介质模型评价与具体盆地的地质背景和成矿期控矿条件研究相结合，才能获得理想的结果. 

Model of Inner and Outer Reductive Media Within Uranium Reservoir Sandstone of Sandstone-Type Uranium Deposits and Its Ore-Controlling Mechanism: Case Studies in Daying and Qianjiadian Uranium Deposits

The Daying and Qianjiadian uranium deposits, the reductive media within uranium-bearing series are divided into inner reductive media and outer reductive media according to its occurrence relationship with uranium reservoir sandstone. The assemblage of the inner and outer reductive media was in favor of the formation of the interlayer oxidation zone and continuous uranium mineralization. It is found that the interlayer oxidation within uranium reservoir sandstone was directly related with the inner reductive media and the reducibility of uranium reservoir sandstone was largely enhanced when the outer reductive media participated in the process of interlayer oxidation. The reductive media outside uranium reservoir sandstone was just as important to uranium mineralization as the reductive media inside uranium reservoir sandstone. Types and abundance of the reductive media inside and outside uranium reservoir sandstone and their spatial distribution were affected by the synsedimentary palaeoclimate and depositional environment of uranium-bearing series which basically constrained the scale of interlayer oxidation zone. The desired results will be achieved during prospecting prediction for the sandstone-type uranium deposit based on evaluation of the model of the double reductive media associated with the studies of geological background and ore-controlling conditions in the uranium mineralization stage.