气体地球化学勘查在巴—麦地区砂岩型铀矿找矿中的应用

Application of gas geochemical exploration in the exploration of sandstone type uranium deposits in the Ba-Mai region

塔里木盆地内部砂岩型铀矿找矿十分迫切。针对该盆地地质构造相对复杂、沉积地层厚度大、勘查手段受到沙漠-荒漠地貌的限制、勘查程度较低和地表成矿信息弱的特点,在巴楚隆起—麦盖提斜坡带地区(巴—麦地区)开展能指示深部地层环境的H_(2)S、CH_(4)、H_(2)、CO_(2)和4He气体地球化学区域测量研究。结果表明,几种土壤气体浓度能够较为清晰地显示各自异常分布范围,并指示盆地地层中可能的铀异常信息,气体地球化学测量方法是一种相对高效的盆地区域地表勘查方法。在综合测区断裂分布、油气藏、水文等地质条件和气体化学反应性质的基础上,分析气体浓度异常成因及分布综合特征,测区东北部、东南部及色力布亚断裂和巴什托断裂所夹持部分地段具有几种气体组份浓度异常叠加,地层中可能发育氧化-还原地球化学障,是有利的找矿预测区,为该地区砂岩型铀矿勘查提供参考依据。

Gas geochemical measurement method is a relatively efficient method for surface soil exploration in basin areas.Tarim basin is regarded as the potential area for sandstone type uranium deposits,but the relatively complex geological structure,thick sedimentary strata and the desert constrain the exploration methods and level.In this paper,the regional(line)geochemical measurement of H_(2)S,CH_(4),H_(2),CO_(2) and 4He was conducted to indicate the deep geological environment for uranium mineralization information in the Bachu Uplift Maigaiti Slope Zone(Ba-Mai region).Several soil gas concentrations clearly presented the respective abnormal distribution ranges in the buried strata.Based on the comprehensive analysis on geological conditions such as fault distribution,oil and gas reservoirs,hydrology,and gas chemical reaction properties,the characteristics and the genesis of gas concentration anomalies were analyzed with the relation of uranium mineralization formation.Gas component concentration anomalies in the northeastern part of the survey area,as well as some sectors sandwiched by the Selibuya and Bashto faults,were found superimposed by several gases,which may be related to the developing oxidation and reduction geochemical barriers favorable for sandstone uranium mineralization.Therefore,the study result provided reference for the exploration of sandstone type uranium deposits in the area.