Multi-stage formation of REE minerals in the Palabora Carbonatite Complex, South Africa

Giebel, R. Johannes; Gauert, Christoph; Marks, Michael A.W.; Costin, Gelu; Markl, Gregor

doi:10.2138/am-2017-6004

Cited by 82 publications

(52 citation statements)

References 61 publications

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“…This substitution and the spatial association of apatite and monazite indicate the growth of the latter at the expense of apatite. A similar mechanism of monazite formation was described for the late-stage carbonatites of the Cummins Range Carbonatite Complex, Australia [7], the Fen complex, Norway [58], the Sokli complex, Finland [152], the Palabora complex, South Africa [65], and others worldwide. Presumably, thorite or huttonite (complementary to monazite) is the product of the selective concentration of elements (Th and HREE) released during apatite decomposition.…”

Section: Late-stage Processesmentioning

confidence: 53%

“…Since the formation of ancylite is controlled by aREE 3+ , aCa 2+ , aSr 2+ , aBa 2+ , aNa + , aF − [65], aCO 3 2− [68,142], and a(OH) − [78] (where "a" is activity), the most important factor for its deposition is fluid chemistry. Ancylite crystallization is possible at relatively low values of aREE 3+ /(aCa 2+ + aSr 2+ + aBa 2+ + aNa + ) (otherwise, carbocernaite is formed [65]), at low values of aF − (otherwise, cordylite is formed [65]), and at high values of aCO 3 2− and a(OH) − (otherwise, synchysite and/or bastnäsite is formed [68,78,142]).…”

Section: The Main Stage Of Ree Mineralization (The Formation Of Ancylmentioning

confidence: 99%

“…The origin of such rocks is attributed to the remobilization of rare-earth elements from alkaline rocks by the late-stage fluids [148]. At the Palabora complex, it was shown that thorium can be used as an indicator of remobilization [65]. In the Palabora carbonatites, Th is abundant in early minerals crystallized during the main stage of REE mineralization.…”

Section: Late-stage Processesmentioning

confidence: 99%

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The Petyayan-Vara Carbonatite-Hosted Rare Earth Deposit (Vuoriyarvi, NW Russia): Mineralogy and Geochemistry

et al. 2020

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The Vuoriyarvi Devonian carbonatite–ijolite–pyroxenite–olivinite complex comprises several carbonatite fields: Neske Vara, Tukhta-Vara, and Petyayan-Vara. The most common carbonatites in the Tukhta-Vara and Neske-Vara fields are calciocarbonatites, which host several P, Fe, Nb, and Ta deposits. This paper focuses on the Petyayan-Vara field, in which the primary magmatic carbonatites are magnesian. The least altered magnesiocarbonatites are composed of dolomite with burbankite and are rich in REE (up to 2.0 wt. %), Sr (up to 1.2 wt. %), and Ba (up to 0.8 wt. %). These carbonatites underwent several stages of metasomatism. Each metasomatic event produced a new rock type with specific mineralization. The introduction of K, Si, Al, Fe, Ti, and Nb by a F-rich fluid (or fluid-saturated melt) resulted in the formation of high-Ti magnesiocarbonatites and silicocarbonatites, composed of dolomite, microcline, Ti-rich phlogopite, and Fe–Ti oxides. Alteration by a phosphate–fluoride fluid caused the crystallization of apatite in the carbonatites. A sulfate-rich Ba–Sr–rare-earth elements (REE) fluid (probably brine-melt) promoted the massive precipitation of ancylite and baryte and, to a lesser extent, strontianite, bastnäsite, and synchysite. Varieties of carbonatite that contain the highest concentrations of REE are ancylite-dominant. The influence of sulfate-rich Ba-Sr-REE fluid on the apatite-bearing rocks resulted in the dissolution and reprecipitation of apatite in situ. The newly formed apatite generation is rich in HREE, Sr, and S. During late-stage transformations, breccias of magnesiocarbonatites with quartz-bastnäsite matrixes were formed. Simultaneously, strontianite, quartz, calcite, monazite, HREE-rich thorite, and Fe-hydroxides were deposited. Breccias with quartz-bastnäsite matrix are poorer in REE (up to 4.5 wt. % total REE) than the ancylite-dominant rocks (up to 11 wt. % total REE).

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Section: Late-stage Processesmentioning

confidence: 53%

Section: The Main Stage Of Ree Mineralization (The Formation Of Ancylmentioning

confidence: 99%

Section: Late-stage Processesmentioning

confidence: 99%

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The Petyayan-Vara Carbonatite-Hosted Rare Earth Deposit (Vuoriyarvi, NW Russia): Mineralogy and Geochemistry

et al. 2020

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“…The REE can be hosted in apatite, a common carbonatite magmatic mineral for which the REE have a strong affinity (e.g. Giebel et al, 2017). Apatite in carbonatites commonly contains over 1 wt.…”

Section: Introductionmentioning

confidence: 99%

Light rare earth element redistribution during hydrothermal alteration at the Okorusu carbonatite complex, Namibia

Cangelosi

Broom-Fendley

Banks

et al. 2019

MinMag

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The Cretaceous Okorusu carbonatite, Namibia, includes diopside-bearing and pegmatitic calcite carbonatites, both exhibiting hydrothermally altered mineral assemblages. In unaltered carbonatite, Sr, Ba and rare earth elements (REE) are hosted principally by calcite and fluorapatite. However, in hydrothermally altered carbonatites, small (<50 µm) parisite-(Ce) grains are the dominant REE host, while Ba and Sr are hosted in baryte, celestine, strontianite and witherite. Hydrothermal calcite has a much lower trace-element content than the original, magmatic calcite. Regardless of the low REE contents of the hydrothermal calcite, the REE patterns are similar to those of parisite-(Ce), magmatic minerals and mafic rocks associated with the carbonatites. These similarities suggest that hydrothermal alteration remobilised REE from magmatic minerals, predominantly calcite, without significant fractionation or addition from an external source. Barium and Sr released during alteration were mainly reprecipitated as sulfates. The breakdown of magmatic pyrite into iron hydroxide is inferred to be the main source of sulfate. The behaviour of sulfur suggests that the hydrothermal fluid was somewhat oxidising and it may have been part of a geothermal circulation system. Late hydrothermal massive fluorite replaced the calcite carbonatites at Okorusu and resulted in extensive chemical change, suggesting continued magmatic contributions to the fluid system.

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“…Processes that govern the enrichment of REE in carbonatites include fractional crystallization of a carbonatitic melt [10], enrichment by orthomagmatic fluids during late magmatic stages i.e. the magmatic-hydrothermal phase [5], dissolution and re-crystallization of primary to secondary carbonatitic minerals, resulting in the REE being concentrated in the latter [8], and supergene enrichment in weathered zones [11].…”

Section: Introductionmentioning

confidence: 99%

Magmatic-Hydrothermal Processes Associated with Rare Earth Element Enrichment in the Kangankunde Carbonatite Complex, Malawi

et al. 2019

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Carbonatites undergo various magmatic-hydrothermal processes during their evolution that are important for the enrichment of rare earth elements (REE). This geochemical, petrographic, and multi-isotope study on the Kangankunde carbonatite, the largest light REE resource in the Chilwa Alkaline Province in Malawi, clarifies the critical stages of REE mineralization in this deposit. The δ56Fe values of most of the carbonatite lies within the magmatic field despite variations in the proportions of monazite, ankerite, and ferroan dolomite. Exsolution of a hydrothermal fluid from the carbonatite melts is evident based on the higher δ56Fe of the fenites, as well as the textural and compositional zoning in monazite. Field and petrographic observations, combined with geochemical data (REE patterns, and Fe, C, and O isotopes), suggest that the key stage of REE mineralization in the Kangankunde carbonatite was the late magmatic stage with an influence of carbothermal fluids i.e. magmatic–hydrothermal stage, when large (~200 µm), well-developed monazite crystals grew. The C and O isotope compositions of the carbonatite suggest a post-magmatic alteration by hydrothermal fluids, probably after the main REE mineralization stage, as the alteration occurs throughout the carbonatite but particularly in the dark carbonatites.

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Multi-stage formation of REE minerals in the Palabora Carbonatite Complex, South Africa

Cited by 82 publications

References 61 publications

The Petyayan-Vara Carbonatite-Hosted Rare Earth Deposit (Vuoriyarvi, NW Russia): Mineralogy and Geochemistry

The Petyayan-Vara Carbonatite-Hosted Rare Earth Deposit (Vuoriyarvi, NW Russia): Mineralogy and Geochemistry

Light rare earth element redistribution during hydrothermal alteration at the Okorusu carbonatite complex, Namibia

Magmatic-Hydrothermal Processes Associated with Rare Earth Element Enrichment in the Kangankunde Carbonatite Complex, Malawi

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