全球稀土成矿理论研究和找矿进展

    Mineralization theory research and prospecting progress of rare earth deposits in the world

    • 摘要: 近年来,全球稀土矿产勘查投资持续增长,但仍不到2012年历史高峰期的一半。从区域上看,目前稀土勘查主要集中在澳大利亚、非洲和拉美地区,占全球稀土勘查预算的比例分别达到42.9%、23.2%和10.1%。勘探企业更加重视磁体稀土(镨钕镝铽)氧化物在总稀土氧化物含量中的比例。每种类型稀土矿、每个稀土矿不同矿段的MREO占比不同,但总体上看,离子型稀土矿的MREO比例较高,而碳酸岩型较低。碱性侵入岩型、碳酸岩型、离子型稀土矿成为勘探的重要类型,同时矽卡岩型稀土矿勘探也取得突破,澳大利亚、美国、瑞典、巴西、马拉维、安哥拉、格陵兰等国家和地区稀土勘探取得了重要发现。格陵兰的坦布里兹-科瓦内湾、马拉维的坎甘昆德、瑞典的基托普,以及巴西的卡尔德拉分别是碱性侵入岩型、碳酸岩型、矽卡岩型和离子型稀土矿的典型代表。科学家们发现,富铁岩浆喷发形成的火山可能富集大量稀土,稀土元素铈在铜、金、银和铀矿化的主要反应过程中发挥了关键作用,能够形成以稀土为主的成矿系列。坦布里兹与科瓦内湾两个稀土矿虽然都与伊里毛萨克碱性侵入体有关,空间位置上分布在该杂岩体的南北两端,但前者铀含量较低,而后者较高,为世界最大铀矿之一。找矿实践表明,“三稀”矿产可以同时在一个矿床出现,比如坦布里兹,这为寻找超大型“三稀”矿床提供了方向和思路。

       

      Abstract: Mineral exploration investment budget of rare earth in the world has continued to grow in recent years, but it is still less than half of the historical peak in 2012. From a regional perspective, most of the rare earth exploration activities are currently occurred in Australia, Africa and Latin America, whose proportion of mineral exploration investment budget of rare earth in the world have reached 42.9%, 23.2%, and 10.1%, respectively. Exploration companies pay more attention to the proportion of magnet-related rare earth elements (praseodymium, neodymium, dysprosium and terbium) oxides (MREO) in the total rare earth oxide (TREO) content. The proportion of MREO varies for each type of rare earth deposit and for different zones in single deposit, but overall, the proportion of MREO is higher for ionic rare earth deposits and lower for carbonatites. Alkaline intrusion, carbonatite, and ionic rare earth deposit have become important types of exploration. At the same time, breakthroughs have been made in skarn-type rare earth deposits. Important discoveries have been made in rare earth exploration in Australia, the United States, Sweden, Brazil, Malawi, Angola, Greenland etc. Tanbreez-Kvanefjeld in Greenland, Kangankunde in Malawi, Gyttorp in Sweden, and Caldeira in Brazil are typical representatives of alkaline intrusion, carbonatite, skarn, and ionic rare earth deposits, respectively. Scientists have discovered that volcanoes formed by the eruption of iron-rich magma may be enriched in large amounts of rare earths. The rare earth element cerium plays an important role in the main reaction processes of copper, gold, silver and uranium mineralization, and can form a mineralization series dominated by rare earths. Although both Tanbreez and Kvanefjeld rare earth deposits are related to the Ilimaussaq alkaline intrusion and spatially distributed at the north and south ends of the complex, the former has a lower uranium content while the latter has a higher, making the later one of the world’s largest uranium deposits. Mineral exploration practice shows that the “three rare” deposits can appear in single deposit at the same time, such as Tanbreez, which provides direction and ideas for prospecting such deposits.

       

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