鄂尔多斯盆地南缘双龙铀矿成矿特征初步探讨
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摘要
铀矿物成矿年龄测定结果显示,双龙铀矿成矿年龄(52. 6±2. 2) Ma,成矿时代为始新世。分析认为,双龙铀矿主要的还原剂是H_2S,它是古近纪时期直罗组下段砂体内有机质演化产生的CH_4气体和下部延安组煤层气、延长组油气逸散到砂体内的CH_4气体,在去硫菌作用下与地下水中SO_4~(2-)发生反应生成;生成的H_2S随地下水运移到背斜、隆起等构造圈闭处聚集,形成强还原环境,还原含氧含铀溶液中的Fe~(3+)和U~(6+); Fe~(3+)总是先于U~(6+)还原沉淀,这就造就了铀矿物围绕黄铁矿分布。电子探针分析认为,双龙铀矿物类型主要为沥青铀矿、铀石及少量钛铀矿。通过对双龙铀矿含矿层位构造(褶皱、隆起、洼陷等)与铀矿化的关系研究,认为含矿层位构造对铀矿形成有明显的控制作用,即铀矿化一般产于隆起与洼陷的过渡部位或者背斜两翼缓坡段。加强鄂尔多斯盆地南缘目的层砂体次生构造的研究对该地区砂岩型铀矿找矿具有很重要的意义。
The results of metallogenic age of uranium ore show:( 52. 6 ± 2. 2) Ma age of Shuanglong uranium mineralization,metallogenic epoch is Eocene. Analysis points out the main reducing agent and precipitation agent of Shuanglong uranium mine are H_2 S. It is generated by CH_4 gas and SO_4~(2-)ions under the action of the sulfur-sulphide bacteria. The CH_4 gas is mainly derived from the evolution of organic matter in the lower section of the Paleogene sand and coalbed methane escape from Yanan formation or oil and gas escape from Yanchang formation.The reaction-generated H_2 S with groundwater movement to the tectonic trap such as anticline,heave,etc. Make it a strong restore environment. Reduction of Fe~(3+)ions and U~(6+)ions in oxygen-containing uranium solution at the gas-water interface. Fe~(3+)ions always precede U~(6+)ion reduction precipitation. This creates the distribution of uranium ore around the pyrite. Electron probe analysis holds that the main types of the Shuanglong uranium ore are asphalt uranium ore,uranium ore and a small amount of titanium uranium ore. Through the study of the relationship between the secondary structure( fold,uplift,sag,etc.) and uranium mineralization of the ore body in Shuanglong uranium mine. It is considered that the secondary structure of ore-bearing ores has obvious control effect on the formation of uranium deposits. In other words,uranium mineralization is usually produced in the transitional area of uplift and sag. Strengthening the structure of ore-bearing position in the southern margin of Ordos basin is very important for prospecting of sandstone-type uranium deposits in this area.
The results of metallogenic age of uranium ore show:( 52. 6 ± 2. 2) Ma age of Shuanglong uranium mineralization,metallogenic epoch is Eocene. Analysis points out the main reducing agent and precipitation agent of Shuanglong uranium mine are H_2 S. It is generated by CH_4 gas and SO_4~(2-)ions under the action of the sulfur-sulphide bacteria. The CH_4 gas is mainly derived from the evolution of organic matter in the lower section of the Paleogene sand and coalbed methane escape from Yanan formation or oil and gas escape from Yanchang formation.The reaction-generated H_2 S with groundwater movement to the tectonic trap such as anticline,heave,etc. Make it a strong restore environment. Reduction of Fe~(3+)ions and U~(6+)ions in oxygen-containing uranium solution at the gas-water interface. Fe~(3+)ions always precede U~(6+)ion reduction precipitation. This creates the distribution of uranium ore around the pyrite. Electron probe analysis holds that the main types of the Shuanglong uranium ore are asphalt uranium ore,uranium ore and a small amount of titanium uranium ore. Through the study of the relationship between the secondary structure( fold,uplift,sag,etc.) and uranium mineralization of the ore body in Shuanglong uranium mine. It is considered that the secondary structure of ore-bearing ores has obvious control effect on the formation of uranium deposits. In other words,uranium mineralization is usually produced in the transitional area of uplift and sag. Strengthening the structure of ore-bearing position in the southern margin of Ordos basin is very important for prospecting of sandstone-type uranium deposits in this area.
引文
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杨理华,李钦祖.1980.华北地区地壳应力场[M].北京:地震出版社:41-62.
张金带,简晓飞,李友良,等.2011.“十一五”铀矿勘查和地质科技进展及“十二五”总体思路[J].铀矿地质,27(1):1-7.
张金带,李子颖.2010.铀矿勘查和地质科技进展与态势[M].北京:原子能出版社:117-221.
张字龙,范洪海,蔡煜琦,等.2016.鄂尔多斯盆地黄陵地区直罗组有机地球化学特征及其与铀成矿关系[J].地质学报,90(12):3408-3423.
(1)罗永坚,马燕杰,张厚冬,等. 1979.陕西省黄陵县八〇四地区铀矿综合研究报告[R].核工业208队:3-21.
陈宏斌,徐高中,王金平,等.2006.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[J].地质学报,80(5):724-731.
陈祖伊,郭庆银.2007.砂岩型铀矿床硫化物还原富集铀的机制[J].铀矿地质,23(6):321-334.
寸小妮,吴柏林,张洪深,等.2016.鄂尔多斯盆地大营铀矿铀的赋存状态研究[J].西北地质,45(2):198-211.
古勃金H B,斯米尔诺夫A A.1985.水成铀矿床的找矿标志和预测基础[M].雷文高,译.北京:原子能出版社:58-92.
侯惠群,李言瑞,刘洪军,等.2016.鄂尔多斯盆地北部直罗组有机质特征及与铀成矿关系[J].地质学报,90(12):3367-3374.
胡俊华,郭科锋.2017.鄂尔多斯盆地南缘砂岩型铀矿找矿潜力分析[J].铀矿地质,33(3):137-143.
秦艳,张文正,彭平安,等.2009.鄂尔多斯盆地延长组长7段富铀烃源岩的铀赋存状态与富集机理[J].岩石学报,25(10):2469-2476.
吴柏林,张婉莹,宋子升,等.2016.鄂尔多斯盆地北部砂岩型铀矿铀矿物地质地球化学特征及其成因意义[J].地质学报,90(12):3393-3407.
邢秀娟,柳益群,樊爱萍.2006.鄂尔多斯盆地店头地区砂岩型铀矿成因初步探讨[J].中国地质,33(6):591-597.
杨理华,李钦祖.1980.华北地区地壳应力场[M].北京:地震出版社:41-62.
张金带,简晓飞,李友良,等.2011.“十一五”铀矿勘查和地质科技进展及“十二五”总体思路[J].铀矿地质,27(1):1-7.
张金带,李子颖.2010.铀矿勘查和地质科技进展与态势[M].北京:原子能出版社:117-221.
张字龙,范洪海,蔡煜琦,等.2016.鄂尔多斯盆地黄陵地区直罗组有机地球化学特征及其与铀成矿关系[J].地质学报,90(12):3408-3423.
(1)罗永坚,马燕杰,张厚冬,等. 1979.陕西省黄陵县八〇四地区铀矿综合研究报告[R].核工业208队:3-21.