鄂尔多斯盆地东北部塔然高勒地区还原介质对砂岩型铀矿的控制

Control of reducing medium on uranium deposit of sandstone in Tarangaole area, northeastern Ordos basin

为明确鄂尔多斯盆地塔然高勒地区直罗组、延安组地层中煤、黄铁矿等还原介质与砂岩型铀矿的共存关系,选取直罗组含矿砂体及其中的黄铁矿、炭屑以及延安组煤层等为研究对象,综合利用钻孔编录、显微镜和电子探针分析等手段开展研究。结果表明,研究区铀矿体与延安组煤层、直罗组炭屑具有空间和成因上的关联,延安组煤层为铀的沉淀提供了大量的还原剂,而直罗组炭屑里的腐植酸对铀酰离子起到吸附和络合的作用;铀石是该区最主要的铀矿物类型,其与莓球状黄铁矿、蚀变黄铁矿、胶状黄铁矿、钛铁矿、白钛石伴生关系明显;有机质、黄铁矿等还原介质的含量及空间分布可以作为铀成矿的指示标志。

In order to clarify the coexisting relationship between the coal,pyrite and other reducing medium in Yan’an and Zhiluo Formation and the sandstone uranium deposit in Tarangaole area,the ore-bearing sand body,pyrite and carbon debris in Zhiluo Formation and coal seam in Yan’an Formation were selected as the research object,a series of test including drilling core catalog,microscope analysis and electron probe analysis were used to carry out research.It has been shown that the uranium ore body,coal seam in Yan’an Formation,carbon debris in Zhiluo Formation are vertically stacked and related in genesis,the coal deposits of Yan’an Formation provide a large amount of reducing agent for uranium deposits,while the humic acid in the charcoal of Zhiluo Formation mainly played the role of adsorption and complexation;Coffinite is the main uranium ore type and has connection with framboidal pyrite,altered massive pyrite,colloidal pyrite,ilmenite,leucoxene;The amount of reducing medium and spatial distribution can be used as indicator of uranium mineralization.