鄂尔多斯盆地南缘店头铀矿床矿化特征及其与东胜铀矿床对比

Mineralization Characteristics of Diantou Uranium Deposit in the Southern Margin of Ordos and in Comparison with Dongsheng Uranium Deposit

店头铀矿床是产于中侏罗统直罗组下岩性段顶部褪色蚀变带与灰色砂岩过渡部位的砂岩型铀矿,矿化严格受褪色蚀变带与灰色岩石界线的控制,矿体形态呈似层状,矿石中铀矿物主要为铀石,并出现一套黄铁矿-黄铜矿-方铅矿-闪锌矿低温热液矿物组合,同时发现少量硒铅矿。铀成矿年龄为98～110Ma1,41.8±9.3Ma,51.0±5.8Ma。通过对店头铀矿床与东胜铀矿床主要特征研究,店头铀矿床的铀成矿地质背景和铀矿化特征与东胜铀矿床较为相似,两个矿床可以对比。但也存在较为明显的差异,店头铀矿床岩石成岩程度较高,东胜铀矿床则较低;店头铀矿床油气显示以中质油为主,而东胜铀矿床以天然气为主。店头铀矿床同东胜铀矿床主要形成于盆地由成盆坳陷向隆升剥蚀转变的过程中(K1末—N2),铀成矿作用由早期渗入层间氧化或层间—潜水氧化作用为主导,转变为晚期深部渗出的含油、气低温热液与地表渗入含氧含铀水相互作用改造、叠加富集铀成矿作用。第三纪晚期之后不再有新的铀矿物生成,主要存在逸散油、气的还原保矿作用。

Diantou uranium deposit is a sandstone-type uranium deposit between fade alteration zoning that top of lower member of Zhiluo formation is in middle Jurassic and gray-color sandstone , mineralization is strictly controlled by boundary between fade alteration zoning and gray-color rock, mineral body is stratoid structure （occurrence in similar beds）, coffinite is main uranium mineral with ehaleopyrite-pyrite-galena-sphalerit epitherrnal mineral assemblage, at same time , a few of clausthalite are found. Uranium mineraogenetic epoch is 98～110 Ma, 41. 8 ± 9. 3 Ma, 51. 0 ±5. 8 Ma. Through study on main characteristics of Diantou uranium deposit in comparison with Dongsheng uranium deposit , geologic background and mineralization characteristics of Diantou uranium deposit is similar to Dongsheng uranium deposit, tow deposit can be compared , but there are some obvious differences, diagenetic grade of Diantou uranium deposit is quite high, but Dongsheng uranium deposit is little bit lower main evidences of oil and gas of Diantou uranium deposit is middling oil, and Dongsheng uranium deposit＇s main is gas. Diantou uranium deposit and Dongsheng uranium deposit are form in process of depression basin to upwarping denudation （K1late-N2）. Uranium metallogenesis is transform and supermineral deposit of action of seeping into uranium and oxygen superwater with seeping out deep hydrocarbon hypothermal fluid each other later come from action of interlayer-groundwater oxido-reduction early, none uranium minerals are produced after later Tertiary, there is protective ore action by escape oil and gas.