Rare Earth Element Ore Geology of Carbonatites

Verplanck, Philip L.; Mariano, Anthony N.

doi:10.5382/rev.18.01

Cited by 59 publications

(89 citation statements)

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“…Rare earth elements (REE: La to Lu), a group of technologically critical metals (Hoatson et al 2011, Atwood 2012, Chakhmouradian & Wall 2012, Linnen et al 2014, Wall 2014, are mostly obtained from carbonatites or carbonatite-related ore deposits (Chakhmouradian & Zaitsev 2012, Verplanck et al 2016. REE-rich carbonatites are commonly hydrothermally altered and overprinted, such that some degree of REE mobility is observed.…”

Section: Introductionmentioning

confidence: 99%

REE Redistribution Textures in Altered Fluorapatite: Symplectites, Veins, and Phosphate-Silicate-Carbonate Assemblages from the Nolans Bore P-REE-Th Deposit, Northern Territory, Australia

Anenburg

Burnham

Mavrogenes

2018

The Canadian Mineralogist

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The geochemical behavior and genesis of rare earth element (REE) ores remains poorly understood. In addition, the processes responsible for many features observed in REE ore deposits are not easily determined. Importantly, the distinction between igneous versus post-magmatic genesis, or the nature of the mineralizing and modifying fluids or melts, remains in dispute. Nolans Bore is a P-REE-Th deposit in the Northern Territory, Australia, hosting REE mineralization in fluorapatite and its alteration products. These mineralization textures are imaged in 3D by X-ray computed tomography and in 2D by electron microscopy, cathodoluminescence, and X-ray mapping. Primary igneous REE-rich fluorapatite was replaced in two stages. The first, at high temperature, was to endmember fluorapatite-britholite symplectite. The second, at lower temperatures, was to hydrothermal veins and patches comprised of REE-Th phosphate, silicate, and carbonate minerals. Quadrivalent Ce occurs together with Th, suggesting oxidized, low-temperature conditions. Strikingly similar textures are observed at Hoidas Lake, Saskatchewan, Canada, where igneous immiscibility or a pegmatitic boundary layer have been implicated in their formation. Our textural and chemical investigations establish that these symplectites and other similar textures are not primary igneous textures, but formed by subsequent cooling and alteration. Understanding the processes that formed these symplectic and vein textures is key to their theoretical and experimental modeling and should lead to a better understanding of ''hydrothermal'' REE deposits globally. The decoupling of Ce from the rest of the REE and the mineralogical preferences of the light REE versus the heavy REE should be considered when evaluating similar ore deposits for their economic value and mineral processing.

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Section: Introductionmentioning

confidence: 99%

REE Redistribution Textures in Altered Fluorapatite: Symplectites, Veins, and Phosphate-Silicate-Carbonate Assemblages from the Nolans Bore P-REE-Th Deposit, Northern Territory, Australia

Anenburg

Burnham

Mavrogenes

2018

The Canadian Mineralogist

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“…Different sources of REE in carbonatites have been proposed: (1) magmatic REE concentrations in the orthomagmatic fluid generated by fractional crystallization [30]; (2) remobilization of REE leached from primary magmatic minerals, such as carbonates or apatite [6,15,59,67,68] where REE are not an essential constituent (Table S2); and (3) remobilization of REE from early magmatic REE minerals, where REE are essential elements of the minerals from an initially REE-enriched melt [7][8][9]. To identify the best source model for the Saint-Honoré REE deposit, the most pristine magmatic Fe-carbonatites were identified.…”

Section: Discussionmentioning

confidence: 99%

“…In general, the HREE concentrations of the Saint-Honoré Fe-carbonatite are relatively similar to non-mineralized carbonatites [10], but the LREE are one to two orders of magnitude higher (Figure 9). The REE patterns are strongly fractionated which is typical of REE deposits in carbonatites [8,9,15,59,60]. In general, based on >15,000 REE analyses performed in the RFeC (IAMGold unreleased data), no significant higher-grade zones or vertical variations exist.…”

Section: Geochemistry Of the Fe-carbonatitementioning

confidence: 93%

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The Saint-Honoré Carbonatite REE Zone, Québec, Canada: Combined Magmatic and Hydrothermal Processes

2018

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The Saint-Honoré carbonatite complex hosts a rare earth element (REE) deposit traditionally interpreted as being produced by late-stage hydrothermal fluids that leached REE from apatite or dolomite found in the early units and concentrated the REE in the late-stage units. New evidence from deeper units suggest that the Fe-carbonatite was mineralized by a combination of both magmatic and hydrothermal crystallization of rare earth minerals. The upper Fe-carbonatite has characteristics typical of hydrothermal mineralization—polycrystalline clusters hosting bastnäsite-(Ce), which crystallized radially from carbonate or barite crystals, as well as the presence of halite and silicification within strongly brecciated units. However, bastnäsite-(Ce) inclusions in primary magmatic barite crystals have also been identified deeper in the Fe-carbonatite (below 1000 m), suggesting that primary crystallization of rare earth minerals occurred prior to hydrothermal leaching. Based on the intensity of hydrothermal brecciation, Cl depletion at depth and greater abundance of secondary fluid inclusions in carbonates in the upper levels, it is interpreted that hydrothermal activity was weaker in this deepest portion, thereby preserving the original magmatic textures. This early magmatic crystallization of rare earth minerals could be a significant factor in generating high-volume REE deposits. Crystallization of primary barite could be an important guide for REE exploration.

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“…The remainder of the papers in this thematic set focus on mineralisation related to carbonatites, which are particularly wellendowed with deposits of several critical raw materials, such as P, Nb, F and the REE in particular (Verplanck et al, 2016). Broom-Fendley et al (2020) present X-ray spectroscopy data investigating the incorporation of sulfur into the structure of monazite-group minerals.…”

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confidence: 99%

Critical metal mineralogy and ore genesis revisited: thematic set arising from the Third International Critical Metals Meeting, Edinburgh

Deady

Broom-Fendley

2020

MinMag

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Rare Earth Element Ore Geology of Carbonatites

Cited by 59 publications

References 0 publications

REE Redistribution Textures in Altered Fluorapatite: Symplectites, Veins, and Phosphate-Silicate-Carbonate Assemblages from the Nolans Bore P-REE-Th Deposit, Northern Territory, Australia

REE Redistribution Textures in Altered Fluorapatite: Symplectites, Veins, and Phosphate-Silicate-Carbonate Assemblages from the Nolans Bore P-REE-Th Deposit, Northern Territory, Australia

The Saint-Honoré Carbonatite REE Zone, Québec, Canada: Combined Magmatic and Hydrothermal Processes

Critical metal mineralogy and ore genesis revisited: thematic set arising from the Third International Critical Metals Meeting, Edinburgh

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