Ion adsorption-type REE deposit associated with the Ambohimirahavavy alkaline complex: potential controls on mineralisation
Ion adsorption-type REE deposit associated with the Ambohimirahavavy alkaline complex: potential controls on mineralisation
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与 Ambohimirahavavy 碱性杂岩有关的离子吸附型稀土矿床：对矿化的潜在控制
DOI：
10.1080/03717453.2017.1306272
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Marquis E
中科院分区：
文献类型：
--
作者：
Marquis E
稀土元素（REE：La-Lu）由于对供应安全的担忧而被强调为“关键材料”。特别是对重稀土元素（HREE：Gd-Lu）的需求在过去十年中有所增加（Wall 2014）。离子吸附型矿床（IAD）为全球市场提供大部分重稀土元素和钇（美国地质调查局，2015年）。含有C以上的。50%的离子可交换稀土元素（+钇），通常吸附在高岭石和埃洛石等粘土矿物的表面，通过浸出提取的容易性使得IAD具有经济可行性（Sanematsu和Watanabe，2016）。具有经济价值的离子吸附型矿床几乎仅限于中国南部的变铝质至弱过铝质花岗岩覆盖区（Sanematsu & Watanabe 2016）。值得注意的是，中国大多数富含HREE的IAD与富含HREE的白云母花岗岩有关，这些花岗岩含有在氘代蚀变过程中形成的易降解的REE矿物（例如氟碳酸盐）（Sanematsu & Watanabe 2016）。富HREE离子吸附型矿床形成的主要控制因素似乎是原岩中存在易风化的含HREE矿物，但对这些矿物如何形成的研究有限。除了IAD，过碱性火成岩是已知的稀土元素的重要来源，特别是有价值的HREE，但处理“硬岩”矿床可能具有挑战性（Mariano & Mariano 2012）。在马达加斯加的Ambohimirahavy，过碱性火成岩已被风化形成离子吸附存款，因此相对容易加工。Ambohimirahavy前景目前是独一无二的，拥有一个公认的离子吸附型存款，该存款开发于碱性以上至过碱性火成岩和火山岩，其中一些携带高达2.24%TREO的稀土矿化（Gilbertson 2013）。离子吸附矿石赋存于原岩之上的红土风化剖面中，
The Rare Earth Elements (REE: La-Lu) have been highlighted as ‘critical materials’ as a result of concerns over the security of supply. In particular demand for heavy REE (HREE: Gd-Lu) has increased over the past decade (Wall 2014). Ion Adsorption-Type Deposits (IADs) supply the majority of HREE and yttrium to the global market (US Geological Survey 2015). Containing more than c. 50% ion exchangeable REE (+ yttrium), typically adsorbed to the surface of clay minerals such as kaolinite and halloysite, it is the ease of extraction through leaching that makes IADs economically viable (Sanematsu & Watanabe, 2016). Economic ion adsorption-type deposits are almost exclusively confined to areas of southern China underlain by metaluminous to weakly peraluminous granites (Sanematsu & Watanabe 2016). Notably the most HREE-enriched IADs in China are associated with HREE-enriched muscovite granites that contain easily degradable REE-minerals (eg fluorcarbonates) formed during deuteric alteration (Sanematsu & Watanabe 2016). The primary control on the formation of HREE-rich ion adsorption type deposits seems to be the presence of easily weathered HREE-bearing minerals in the protoliths, but there has been limited study of how these minerals form. Other than IADs, peralkaline igneous rocks are known to be a substantial source of REE, especially the valuable HREE but processing the ‘hard-rock’deposits can be challenging (Mariano & Mariano 2012). At Ambohimirahavavy, Madagascar, peralkaline igneous rocks have been weathered to form an ion adsorption deposit which is thus relatively easy to process.The Ambohimirahavavy prospect is currently unique in hosting a recognised ion adsorption-type deposit developed above alkaline to peralkaline igneous and volcanic rocks, some of which carry REE mineralisation of up to 2.24% TREO (Gilbertson 2013). The ion adsorption ores are present within lateritic weathering profiles above these protoliths, and carry an aver-