Abstract

The Qinglong uranium ore field, including the Gangou and Panlingtou uranium deposits, is situated on the northern margin of the North China Craton (NCC). The Haifanggou Formation is a major uranium-bearing horizon in the ore field. We conducted petrographic, geochemical, electron probe, and high-resolution scanning electron microscope studies aimed at analyzing granite conglomerate samples of the Shigaizi ore-bearing horizon, which is located in the western Qinglong uranium ore field. We determined the geodynamic evolution and mineralization of the region by comparing the Gangou and Panlingtou uranium deposits. Geochemically, the granite conglomerate has a high silica content (62.53 wt %–74.70% wt %) and is rich in alkalis (4.41–7.98 wt %) and Al₂O₃ (7.62–17.58 wt %) but poor in MgO (0.35–3.01 wt %) and CaO (0.17–1.80 wt %). It exhibits a weak negative Eu anomaly (0.81–1.12), is enriched in LREEs, Rb, Th, U, and K and severely depleted in Nb, Ta, Ti, and P, indicating that it is similar to I-type granite and has the characteristics of adakitic rocks. The main uranium mineral is pitchblende, which is associated with pyrite, organic matter (soot), and calcite. The Shigaizi ore-bearing horizon displays many similarities with the Gangou and Panlingtou uranium deposits. Common features include the whole-rock compositions and mineral chemistry. Based on these results and the evolution of the northern NCC, we suggest that the granite conglomerate formed in an active continental margin environment and have a great prospecting potential. The lack of deep prospecting may be the main reason why the concealed large and thick orebodies remain undiscovered.

中文翻译：

---

石盖子地区青龙西部铀矿田含矿花岗砾岩地球化学特征、构造背景及其与铀成矿的关系

摘要

青龙铀矿田，包括干沟和盘岭头铀矿床，位于华北克拉通（NCC）的北缘。海防沟组是矿田中一个主要的含铀层位。我们进行了岩相学、地球化学、电子探针和高分辨率扫描电子显微镜研究，旨在分析位于西青龙铀矿田的石盖子含矿层位的花岗岩砾岩样品。我们通过比较甘沟和盘岭头铀矿床确定了该地区的地球动力学演化和​​成矿作用。地球化学上，花岗岩砾岩的二氧化硅含量高（62.53 wt %–74.70 wt %），富含碱（4.41–7.98 wt %）和Al ₂ O ₃（7.62-17.58 wt%），但缺乏 MgO（0.35-3.01 wt%）和 CaO（0.17-1.80 wt%）。呈现弱负 Eu 异常（0.81-1.12），富含 LREEs、Rb、Th、U 和 K，严重贫化 Nb、Ta、Ti 和 P，表明它类似于 I 型花岗岩和具有埃达克质岩石的特征。铀的主要矿物是沥青铀矿，与黄铁矿、有机物（煤烟）和方解石有关。石盖子含矿层位与干沟和盘岭头铀矿床有很多相似之处。共同特征包括全岩成分和矿物化学。基于这些结果和华北克拉通北部的演化，我们认为花岗岩砾岩形成于活跃的大陆边缘环境，具有很大的找矿潜力。