二连盆地咸拉嘎凹陷土壤氡异常特征及铀成矿预测

    Radon anomaly characteristics in the soil and uranium metallogenic prediction in Xianlaga depression of Erlian Basin

    • 摘要: 二连盆地是我国北方重要的砂岩型铀矿产地,前人在其内部的咸拉嘎凹陷周边及临区发现了多个中大型铀矿床,显示了较好的铀矿找矿前景。在工作区开展面积性土壤氡及其子体测量,通过分析异常数据,并与二连盆地已知铀矿床氡气异常测量模型进行对比及钻探查证。通过土壤氡气测量,在工作区圈定了3个氡及其子体异常区,结合已有铀矿氡异常模型,择优在M1异常高值区部署了钻孔进行查证。在ZKX-1钻孔赛汉组下段砂岩中发现了多段氧化蚀变现象,与异常模型预测一致,显示了较好的铀矿找矿前景。分析结果显示: M1异常区由潜水—层间氧化或层间氧化强烈发育所致,在高值区两侧的氡浓度偏低晕或背景值区内可能存在铀矿化富集,值得开展进一步探索; M2和M3异常区可能与潜水氧化有关,异常强度大小受砂体氧化被改造后的松散程度和渗透性控制,M2和M3异常区之间的Y3铀成矿远景区是有利的找矿部位。研究成果指示该凹陷有较好的铀成矿潜力,可为下一步铀矿找矿方向提供参考。

       

      Abstract: Erlian Basin is important sandstone-type uranium deposits in Northern China. Many medium-scale and large-scale uranium deposits have been found in the periphery and adjacent areas of Xianlaga depression, indicating favorable uranium prospecting potential. The authors conducted measurement of radon in the soil and its daughters for obtaining the information of weak (uranium) mineralization on the surface of the depression, The anomaly data were analyzed and compared with of the known radon anomaly measurement model of the uranium deposits in Erlian Basin, and the drilling verification was carried out. Three anomaly areas of radon and its daughters were delineated in the working area based on soil radon gas measurement. Combined with the known anomaly models of uranium deposits, drilling holes were deployed in M1 anomaly high value area to verify the superiority. Multistage oxidation alteration was found in the sandstone of the Lower Saihan Formation in ZKX-1 borehole, and it was consistent with the prediction of the anomaly model, indicating favorable uranium prospecting potential. It is considered that the M1 anomaly area is caused by the strong development of phreatic interlayer or interlayer oxidation, and uranium mineralization enrichment may exist in the low halo or background value area of radon concentration on both sides of the high value area, which is worthy of further exploration. The M2 and M3 anomaly areas may be related to phreatic oxidation, and the intensity of the anomaly is controlled by the porosity and permeability of the oxidized sand body. The Y3 uranium prospective area between the M2 and M3 anomaly areas are favorable prospecting areas. This research shows that the depression has good uranium metallogenic potential and cound provide references for the further uranium prospecting.

       

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