准噶尔盆地南缘头屯河地区砂岩型铀矿成矿环境与找矿方向

Metallogenic Environment and Prospecting Direction of Sandstone Type Uranium Deposits in Toutunhe Area,Southern Margin of Junggar Basin

为了进一步拓展准噶尔盆地南缘的找矿空间,文章依据准噶尔盆地南缘头屯河地区的最新勘查进展,从中、新生代构造演化历史、蚀源区铀源条件、古气候环境及有利沉积建造、有利目标层位砂体及氧化带发育特征等方面系统分析了研究区砂岩型铀矿成矿条件。研究认为:北天山的富铀地质体和下白垩统清水河组底部砾岩层为该区铀成矿提供了丰富的铀源;形成于温暖潮湿气候的含煤碎屑岩建造,为铀成矿提供了良好的容矿空间;构造掀斜为含铀含氧水的渗入改造提供了构造条件,也为大规模的层间氧化带的发育提供了物质基础。最后提出在头屯河地区强构造变形区寻找第二成矿斜坡带的找矿新思路,将找矿方向从不利于保矿的山前褶皱冲断带转移至第一排构造带末端的单斜区,主要的找矿目标层位为中侏罗统头屯河组和下白垩统清水河组,找矿类型为古层间氧化带型叠加油气-潜水氧化型和潜水氧化型。

In order to further expand the prospecting space in the southern margin of the Junggar Basin,based on the latest exploration progress in Toutunhe area,this paper systematically analyzed the ore-forming conditions of the sandstone type uranium deposits such as tectonic evolution history of Mesozoic and Cenozoic,uranium source conditions,paleoclimatic environment,favorable sedimentary formation and target horizon and development characteristics of sand body and oxidation zone.It was suggested that 1)The uranium-rich geological body in the middle and northern Tianshan and conglomerates at the bottom of the Lower Cretaceous Qingshuihe Formation supply abundant uranium sources for uranium mineralization in this area;2)The coalbearing clastic rock formation formed in warm and humid environment provides a good ore-bearing space for uranium mineralization;3)The structural tilting brings the conditions for the infiltration and transformation of uranium-bearing oxidizing water,and also provides the material foundation for the development of large-scale interlayer oxidation zone.In addition,new prospecting ideas for finding the second metallogenic slope zone was proposed in the strong deformation zone of Toutunhe area and shift the prospecting direction from the fold thrust belt that is not conducive to ore preservation to the monoclinic zone near the second row of structural belts.Finally,this paper profound that the main prospecting target horizons are the Middle Jurassic Toutunhe Formation and Lower Cretaceous Qingshuihe Formation and the ore prospecting type is paleo-interlayer oxidation zone superimposed oil and gas-phreatic oxidation type and phreatic oxidation type.