510-1铀矿床垂直分带规律的发现及其成因意义

Discovery of Vertical Zoning in the 510-1 Uranium Deposit and its Geological Implications

510-1铀矿床中与成矿有关的石英、方解石脉在空间分布上显示出与华南地区花岗岩型铀矿床相似的"上酸下碱"的垂直分带规律。矿床上部(1中段)为"酸帽",主要发育石英脉;中部(2～4中段)为"酸碱共生带",石英脉与方解石脉均较发育;而下部(5～6中段及以下)则为"碱性基底",大量发育方解石脉,未见石英脉,表明矿床第5中段附近(距现今地表深约200m)为"酸碱分离"的地球化学界面。由矿床浅部向深部,总体上方解石中Sr、Zr、Ba、Zn、U、Ni、Cr等微量元素的含量明显增加,其中第5中段附近为多种微量元素的聚集地带。方解石、石英的δCe、δEu值垂向变化也反映出5中段附近为成矿流体演化的氧化还原过度带,与矿床"酸碱分离"的界面一致,暗示这一部位为一重要的流体成矿地球化学界面,亦是铀发生突发成矿作用产生高度富集的部位。垂直分带规律显示出该矿床属于典型的热液矿床,深部找矿潜力还很大。

We found for the first time the vertical zoning rule of gangue minerals （quartz and calcite） in the 510-1 uranium ore deposit that shows an acid top and alkaline bottom. Quartz veins developed on the top of the ore deposit （level No.1）,both of quartz veins and calcite veins are in the middle （level No.2 to No.4）,while on the bottom of the ore deposit （level No.5 to No.6 and below）,only calcite veins are present but no quartz vein was found. The research indicates that there exist a geochemical interface for acid and alkali isolation nearby No.5 level of the 510-1 uranium deposit （200m or so below present earth surface）,which is also a high concentration position for uranium outburst of mineralization. These results have broken the traditional theory on ore-forming of carbonaceous-siliceous-argillitic rock type uranium deposits. They have extremely important significance for ore exploration and prediction in the Zoige region in the future. Meanwhile,they are also an en enlightenment to exploration of other carbonaceous-siliceous-argillitic rock types of uranium deposits.