摘要:
砂岩型铀矿是一类重要的铀矿资源,而遥感是一种重要的矿产资源勘查方法。由于砂岩型铀矿多形成于地下,地表常被沉积物覆盖。这种情况下,遥感是否能在砂岩型铀矿勘查中发挥作用成为值得探讨的问题。本研究以巴音戈壁盆地银根地区为研究对象,在获取Sentinel2,Landsat7 ETM+,ASTER,ALOS DEM以及航空放射性数据的基础上,开展了地形可视化、构造解译、K-T变换、归一化植被指数(normalized difference vegetable index,NDVI)计算、蚀变矿物提取、Th/U比值计算等工作,并从次生还原砂岩型铀矿的成矿模式、条件与控矿要素出发,对结果进行综合分析。分析表明,银根地区中部为隆起带而东南部为凹陷带,两者间为斜坡带。隆起带花岗质岩石可作为重要的铀源。斜坡带上发育的多条近东西走向的断裂构造为含铀含氧水向地下迁移创造了条件。凹陷区发育的断裂富水带和强地表蒸发作用为含铀含氧水排泄蒸发以及驱动地下水循环创造了条件。因此,银根地区隆起带、斜坡带、凹陷带构成一套完整的含铀含氧水循环体系。综合前人资料,认为中部斜坡带可能是一处较好的形成次生还原砂岩型铀矿的地段。本研究也说明,即便在覆盖严重的地区,遥感技术依然可从识别成矿条件与控矿要素的角度,为砂岩型铀矿找矿提供指引。
Abstract:
Sandstone-type uranium deposits emerge as important uranium resources, while remote sensing is identified as a vital method for mineral resource exploration. Since sandstone-type uranium deposits typically occur underground and tend to be covered by sediments, whether remote sensing can be effectively applied to the exploration of such deposits merits investigation. This study investigated the Yingen area in the Bayingobi basin. Utilizing multi-source remote sensing data from Sentinel2, Landsat7 ETM+, ASTER, ALOS DEM, and airborne radioactivity measurements, this study performed terrain visualization, structural interpretations, K-T transformation, NDVI index calculation, alteration mineral extraction, and Th/U ratio calculation. The results were then comprehensively analyzed from the perspective of the metallogenic model, metallogenic conditions, and ore-controlling factors of secondary reduced sandstone-type uranium deposits. The analytical results indicate that the Yingen area consists of an uplift zone in the center, a depression zone in the southeast, and a slope zone between them. The granitic rocks in the uplift zone are identified as significant sources of uranium. Multiple EW-trending faults in the slope zone facilitate the migration of uranium-bearing oxidized water underground. Additionally, the water-rich areas in the depression zone, combined with strong surface evaporation, create favorable conditions for the drainage and evaporation of uranium-bearing oxidized water, further promoting groundwater circulation. Therefore, the uplift zone, slope zone, and depression zone in the Yingen area form a complete circulation system for uranium-bearing oxidized water. In combination with previous data, this study holds that the slope zone might serve as a favorable area for the formation of secondary reduced sandstone-type uranium deposits. This study also demonstrates that even in seriously overburden areas, remote sensing can provide valuable guidance for uranium exploration by identifying metallogenic conditions and ore-controlling factors.
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