摘要:
彭阳铀矿位于鄂尔多斯盆地西南缘, 是全球首例在风成沉积环境中发现的大型砂岩型铀矿, 具有含矿层位深、砂体厚度大、铀矿品位高等特点。通过对彭阳铀矿地质特征、物源、铀源、铀矿物赋存状态、蚀变矿物、烃类流体参与成矿等方面进行研究, 结合前人研究成果, 系统总结了彭阳铀矿的成矿规律。综合研究表明, 研究区深大断裂发育、拥有厚大砂体及稳定的“泥-沙-泥”结构, 对铀成矿极为有利。同时, 盆地西缘岩体可提供稳定铀源, 浅层富氧含铀流体顺层流动、下渗, 深部烃类流体沿断裂上升至洛河组, 导致红色砂岩褪色蚀变, 为铀成矿提供还原剂。中新世到更新世, 构造活动引发了富氧含铀流体和深层含烃流体的耦合作用, 形成了完整的“补-径-排”流体成矿系统, 最终导致铀成矿。通过分析彭阳铀矿的成矿和控矿要素, 进而建立了成矿模式, 对鄂尔多斯盆地西南缘砂岩型铀矿找矿及其它地区相似地质条件下找矿勘查与研究具有重要指示意义。
Abstract:
Pengyang uranium deposit is located in the southwest margin of Ordos Basin. It is the first large-scale sandstone type uranium deposit found in the aeolian sedimentary environment in the world. It has the characteristics of deep uranium bearing beds, thick sand bodies, and high uranium radioactivity. Based on the systematic study of the geological characteristics, material source, uranium source, occurrence state of uranium minerals, altered minerals, and the involvement of hydrocarbon fluids in the mineralization of Pengyang uranium deposit, the metallogenic regularity of Pengyang uranium deposit is systematically summarized in combination with previous research results. The study shows that the deep and large fractures, thick sand bodies and stable “mud-sand-mud” structure in the study area are very favorable for sandstone-type uranium mineralization. At the same time, the rock mass in the west of the basin can provide a stable uranium source, the shallow oxygenated uranium bearing fluid flows and penetrates along the layer, and the deep hydrocarbon fluid rises to the Luohe formation along the fault, leading to the fading and alteration of red sandstone and providing a reducing agent for uranium mineralization. During the Miocene to Pleistocene, tectonic activities triggered the coupling of oxygenated uranium bearing fluids and deep hydrocarbon bearing fluids, forming a complete fluid metallogenic system of “supplement-channel-discharge”, which ultimately led to uranium mineralization. Based on the analysis of the metallogenic factors and ore-controlling factors of Pengyang uranium deposit, a metallogenic model has been established, which is of great significance for the prospecting and research of sandstone type uranium deposits in the southwest margin of Ordos basin and similar geological conditions in other areas.
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