黑龙江省漠河市782高地铌多稀有金属矿床的地质特征及找矿标志

Geological characteristics and prospecting indicator of No.782 highland Nb-rich rare-metal deposit in Mohe City,Heilongjiang Province

黑龙江省漠河市782高地铌多稀有金属矿床位于漠河市北偏西38 km处,是近年来在大兴安岭北部发现的一个铌资源量达到中型规模的矿床,也是至今在黑龙江省内发现的唯一的铌多稀有金属矿床。矿床的大地构造位置处于额尔古纳地块,漠河前陆盆地与富克山-兴华变质基底杂岩的交接部位。区域地球化学分析显示与稀有金属有关的元素组合为U、Th、Nb、Be;区域地球物理特征表明该区处于航空放射性高场中。勘查结果表明,稀有金属矿化产于晚寒武世—早奥陶世碱长花岗岩顶部,呈似层状、板状产出,矿床Nb2O5、Ta2O5、Y2O3、ZrO2平均品位分别为0.12%、0.0087%、0.108%、0.80%,最高品位分别为0.529%、0.0354%、0.309%、1.18%。主要围岩蚀变为钠长石化,铌等稀有金属矿化与其呈正相关关系。初步研究表明,该矿床形成于早奥陶世拉张伸展背景之下,与该时期板块裂解有关,为一处岩浆晚期自交代矿床。文章旨在分析和讨论该矿床的产出地质环境、矿床地质特征和找矿标志,为额尔古纳地块相似类型的矿床的勘查提供理论参考。

The No. 782 highland Nb-rich rare-metal deposit is located in 38 km northwest of Mohe City. The deposit is medium-sized in niobium and is the only Nb-rich rare-metal deposit that has been discovered in Heilongjiang Province so far. This deposit is located in the Erguna block, the junction of Mohe foreland basin and FukeshanXinghua metamorphic basement complex. The regional geochemical survey shows that the element association about rare element are U, Th, Nb, Be, whereas the regional geophysical features indicate characteristics of high airborne radioactive field. The orebody that hosts the rare metals occurs in a Late Cambrian-Early Ordovician tabular-shaped alkali-feldspar granite. The average grade of Nb2 O5, Ta2 O5, Y2 O3,ZrO2 are 0.12%, 0.0087%, 0.108%and 0.80%, respectively, with the highest grade of 0.529%, 0.0354%, 0.309% and 1.18%, respectively. The mineralization of rare metals is positively related to albitization, which is the most important wall rock alteration. Preliminary studies show that No. 782 highland deposit was dominated by an extensional tectonics triggered by the continental rift during the Early Ordovician. The authors comprehensively analyzed the regional geological setting and geological characteristics of the deposit and prospecting indicator so as to provide a theoretical reference for the exploration of similar types of deposits in the Erguna block.