内蒙古克鲁伦断陷盆地可地浸砂岩型铀矿成矿条件分析

Analysis on metallogenic conditions of ISL-amenable sandstone-type uranium deposits in Kelulun down-faulted basin,Inner Mongolia

克鲁伦断陷盆地是海拉尔盆地内部的次级构造单元,位于海拉尔盆地西南缘,是一个近NE方向展布的长条形盆地,面积约2000 km2。克鲁伦断陷盆地北西缘是一个构造斜坡带,具有完整独立的地下水补给、径流和排泄条件;基底岩石不但原始铀含量高,而且其中大部分的铀经后生改造能够被活化释出;克鲁伦断陷盆地古气候经历了温湿干旱炎热的演化过程,是可地浸砂岩型铀矿成矿的有利古气候条件。克鲁伦盆地的找矿目的层是下白垩统大磨拐河组上段,该段存在较好的砂体条件。克鲁伦盆地存在潜水氧化带型和潜水层间氧化带型两种铀矿化类型。因此,克鲁伦断陷盆地存在较好的铀矿成矿条件,具有进一步找矿的潜力。

Kelulun down faulted basin is a secondary tectonic unit of Hailaer basin. It is located at the southwestern margin of the Hailaer basin and is a rectangular-shaped basin stretching in NE direction with an area of about 2000 km2. The northwestern margin of the basin is a tectonic slope with a complete and independent recharge-run off-discharge system of groundwater. Basement rocks are characterized by high original uranium content, moreover, most uranium in basement rocks may be reactivated and released during epigenetic reworking process. The paleoclimate in Kelulun basin experienced an evolution from mild-humid to hot-arid period, being favorable for the metallogenesis of ISL-amenable sandstone- hosted uranium deposits. The upper member of the Damoguaihe Formation, Lower Crtaceous is regarded as the prospecting target in Kelulun basin because favorable sand bodies occur in the member. Two uranium mineralization types have been recognized, namely the interlayer oxidation zone type and the phreatic oxidation type. In a word, favorable uranium metallogenic conditions exist in Kelulun downfaulted basin. It is of further prospecting potential.