鄂尔多斯盆地南部X探区砂岩型铀成矿地质条件及成矿机理分析

Geological condition and metallogenic mechanism of sandstone type uranium deposit in X exploration area,southern Ordos basin

为加强“油-铀”兼探,了解油气矿权区内砂岩型铀矿的资源潜力,在鄂尔多斯盆地内开展了以砂岩型铀矿为勘查对象的老井复查工作,在盆地东南缘X探区发现一批放射性高异常钻井。研究认为,该区具有一定的铀资源潜力。以该区西北部L地区和中部T地区放射性异常特征为基础,对其成矿地质条件进行了细致的分析。研究表明,该区位于构造斜坡带,地层平缓,铀源丰富,古气候适宜,砂体稳定发育,具有完整的补-径-排系统和良好的铀成矿地质条件。通过铀成矿机理研究,研究区内砂岩型铀成矿过程可分为沉积预富集阶段、古层间氧化作用成矿阶段和氧化-还原作用成矿保矿阶段。

In order to strengthen the integration exploration of“oil-uranium”and understand the resource potential of sandstone type uranium deposits in the oil and gas prospecting areas,in 2016,SINOPEC carried out the re-examination of the old Wells in the Ordos basin to explore the sandstone type uranium deposit,and a batch of highly abnormal radioactive wells were found within the X exploration area in the southeastern margin of the basin,which was considered to have certain uranium resource potential.Based on the radiological anomaly characteristics of L sector in the northwest of X exploration area and T sector in the middle of the exploration area,this paper made a detail analysis of its metallogenic conditions.The results showed that this area bears favorable geological conditions for uranium mineralization,such as the structural slope zone,gentle strata,abundant uranium sources,suitable paleoclimate,stable sand body,complete groundwater system of recharge-runoff-discharge.The metallogenic process of sandstone type uranium in the study area can be divided into sedimentary pre-enrichment stage,paleo-interlayer oxidation metallogenic stage and oxidation-reduction metallogenic preserving stage.