中文摘要：

砂岩型铀矿床是一种具有重要经济价值的铀矿类型，受到世界各国地质勘探部门的高度关注。通过电子探针、a径迹蚀刻、逐级化学提取等方法的联合应用，对鄂尔多斯盆地HJQ砂岩型铀矿铀的赋存状态进行研究。结果表明，该地区铀矿物以铀石为主，还有极少量的钍铀石和钛铀矿，这些矿物主要是以微粒吸附形式存在（1～5μm）．部分呈较大铀石微粒集合体形式存在的铀矿物颗粒主要存在于黄铁矿、绿泥石、方解石及有机质的裂隙中，还有少数存在于石英、褐铁矿、云母等矿物的裂隙之中。逐级化学提取实验进一步证实，铀矿物占很大比例，约为50％。分散吸附态的铀约占50％。在分散吸附态的铀中又以黄铁矿和有机质吸附为主，其他矿物吸附的铀在分散吸附的铀中约占5％。

英文摘要：

Because of its important economic value, sandstone--type uranium deposit have been highly concerned by geology exploration department around the world. The paper mainly studied the occurence state of Uranium in sandstone-type Uranium deposits in the Ordos Basin, using methods of electron probe, sequential extraction procedure and a-track etching. The results show that the Uranium ore is rich in coffinite, and contains very small amounts of uranothorite and brannerite, which mainly exist as adsorbed particles （1-5 μm）. Part of the Uranium particles, presenting as larger microparticle assemblages, mainly exist in pyrite, chlorite, calcite and the cracks of organic matter, and a few of them appear in the cracks of quartz, limonite, mica and other minerals, a-track etching further confirms that the percentage of Uranium ore in the deposit is up to 50%, in which the dispersive adsorbed Uranium accounts for about 50%. Whatls more, the dispersive absorbed uranium is basically found in pyrite and organic matter, adsorption to other minerals is just about 5%.