大庆长垣南端GQ地区砂岩型铀矿找矿预测:三维反射地震证据

    Prospecting Prediction for Sandstone-Type Uranium Deposits in GQ Area at the Southern End of Daqing Placanticline: 3D Reflection Seismic Evidence

    • 摘要: 油田地质调查和钻孔资料表明松辽盆地北部大庆长垣南端GQ地区铀异常特征明显,部分钻孔揭示铀矿化已达工业品位,显示该区具有较大铀成矿潜力。但主要赋矿层位四方台组砂岩分布特征还不清楚,制约了该区进一步找矿突破。查明该区盆地三维地质结构和含矿砂岩体发育特征是成矿预测的关键,为此,我们在该区开展了高精度三维反射地震探测,获得了GQ地区50km2三维地震数据体。通过数据精细处理、测井曲线重构、联合水平切片等数据处理解释技术,揭示了四方台组上、中、下三段砂层的厚度及平面分布特征,进一步解译出与砂岩型铀矿密切相关的“泥—砂—泥”地层结构、构造、岩性—岩相等成矿信息。发现研究区四方台组埋深南高北低、厚度南薄北厚,四方台组下段底部砂体厚度大而稳定、连通性较好,与上覆地层四方台组中段底部和下伏地层嫩江组五段细碎屑沉积构成稳定的“泥—砂—泥”地层结构,有利于成矿。综合分析砂岩型铀矿成矿要素,认为砂体厚度20m以上区域为成矿有利区,据此圈定出铀找矿靶区6处,5处推断被后期钻探证实。

       

      Abstract: Oilfield geological surveys and drilling data reveal distinct uranium anomalies in the GQ region of the northern Songliao Basin, specifically at the southern end of the Daqing Placanticline. Some drillings indicate that uranium mineralization has reached industrial grades, indicating significant potential for uranium metallogenesis in this area. However, the distribution characteristics of the main ore-bearing layer, the Sifangtai Formation sandstone, remain unclear, impeding further exploration breakthroughs in the region. Identifying the 3D geological structure and the developmental characteristics of ore-bearing sandstone bodies in the basin is crucial for mineralization predictions. Therefore, we conducted high-precision 3D reflection seismic exploration in the area and acquired a 50km2 3D seismic data volume in the GQ region. Through detailed data processing, well logging curve reconstruction, and combined horizontal slicing, we revealed the thickness and planar distribution characteristics of sand layers in the upper, middle, and lower sections of the Sifangtai Formation. This led to the interpretation of the "mud sand mud" stratigraphic structure, structure, lithology, and rock equivalence closely related to sandstone-type uranium deposits. The study found that the Sifangtai Formation has a higher burial depth in the south and lower depth in the north, with thinner thicknesses in the south and thicker in the north. The sand body at the bottom of the lower section of the Sifangtai Formation is thick and stable, with good connectivity. It forms a stable "mud sand mud" stratigraphic structure with fine clastic sediments from the middle section of the Sifangtai Formation and the fifth section of the Nenjiang Formation, which is conducive to mineralization. A comprehensive analysis of sandstone-type uranium metallogenic factors suggests that areas with sand body thicknesses exceeding 20m are favorable for mineralization. Consequently, six uranium exploration target areas have been delineated, with five inferred to be confirmed by later drilling.

       

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