Lithogeochemical Vectors for Hydrothermal Processes in the Strange Lake Peralkaline Granitic REE-Zr-Nb Deposit

Gysi, Alexander P.; Williams‐Jones, Anthony E.; Collins, Patrick C.

doi:10.2113/econgeo.111.5.1241

Cited by 72 publications

(65 citation statements)

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“…It would also 577 indicate that ƒO 2 was no longer buffered by Reaction 3 and that alteration of arfvedsonite to 578 aegirine had ceased before entrapment of Group 3 inclusions. Gysi et al (2016) showed that 579 arfvedsonite in the Strange Lake granites and pegmatites underwent three types of alteration, 580 namely pervasive replacement by aegirine, core-replacement by hematite and rim replacement by 581 aegirine ± hematite. We propose that these different types of alteration reflect different physico-582 29 chemical conditions, and that at relatively high temperature arfvedsonite was replaced by 583 aegirine, whereas at lower temperature it was replaced by aegirine and/or hematite.…”

Section: (Reaction 3) 572mentioning

confidence: 99%

Fluid evolution in the Strange Lake granitic pluton, Canada: Implications for HFSE mobilisation

2016

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10Strange Lake is a mid-Proterozoic peralkaline granite pluton (Québec-Labrador, Canada) that 11 underwent extreme enrichment in high field strength elements (HFSE), including the rare earth 12 elements (REE). The HFSE mineralisation is confined to highly altered pegmatites and the most 13 altered parts of the granites, implying a genetic association between hydrothermal fluids and 14 HFSE enrichment. This study uses analyses of fluid inclusions to investigate the hydrothermal 15 evolution of the Strange Lake pluton and the role of hydrothermal processes in concentrating the 16 HFSE to potentially exploitable levels. 17Five groups of inclusions were distinguished. From earliest to latest, these groups are: primary 18 aqueous inclusions (~25 wt.% NaCl eq.) associated with melt inclusions (Group 1); primary 19 Fluid evolution commenced with the exsolution of a saline aqueous liquid (~25 wt.% NaCl eq.) 28 and an immiscible CH 4 +H 2 gas from the pegmatitic melt at temperatures of ~450-500 °C and a 29 pressure of ~1100 bars. During isobaric cooling, the gas component of the fluid was gradually 30 oxidised, evolving from being CH 4 -dominant to a CH 4 fluid with a significant proportion of 31 higher order hydrocarbons (due to oxidative coupling of methane induced by the consumption of 32 O 2 through the alteration of arfvedsonite to aegirine; ~325-360°C), and finally to a CO 2 -33 dominated fluid at ~300 o C. The apparent salinity of the aqueous fluid decreased from ~25 to 34 ~4.5 wt.% NaCl eq. due to fluid-rock interaction. The latter also caused precipitation of nahcolite 35 (as a result of the reaction of newly formed CO 2 with sodium from decomposing minerals), 36 formation of pseudomorphs after primary Na-zirconosilicates and Na-titanosilicates and 37 replacement of primary REE-silicates by bastnäsite-(Ce). Owing to this interaction, the carbonic 38 component of the fluid was consumed which, together with the consumption of H 2 O to form Al-, 39 K-and Fe-phyllosilicates, contributed to an increase in the fluid salinity (up to ~19 wt.% NaCl 40 eq.). 41 3 Light rare earth elements (LREE) were remobilised over 10s to 100s of metres by the high 42 temperature high salinity fluid (preserved as Group 1 and 2a inclusions), whereas heavy rare 43 earth elements (HREE) were remobilised on a much smaller scale by a late, low temperature 44 high salinity fluid (trapped as inclusion Group 5). Fluid preserved as inclusion Group 3 may have 45 been responsible for remobilisation of Zr and Ti. 46

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Section: (Reaction 3) 572mentioning

confidence: 99%

Fluid evolution in the Strange Lake granitic pluton, Canada: Implications for HFSE mobilisation

2016

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“…The REE commonly occur in trace concentrations in the earth's crust [3], while economic REE deposits typically are associated with carbonatite and alkaline/peralkaline igneous systems at intraplate tectonic settings. Prominent examples include Bayan Obo in China [2], Strange Lake and Nechalacho in Canada [4][5][6][7], Mountain Pass, CA [8], and Bear Lodge, WY, in the USA [9].…”

Section: Introductionmentioning

confidence: 99%

“…Numerous studies have also indicated the importance of hydrothermal processes for the mobilization and concentration of the REE in the late magmatic evolution stages of carbonatite and alkaline/peralkaline systems [4,5,[16][17][18][19]. Secondary REE enrichment can be significant in the late stages of pluton emplacement, as evidenced by the Strange Lake REE-Zr-Nb deposit in Canada, where metasomatic processes led to hydrothermal mobilization and mineralization of the REE at the periphery of the pluton [4,5,16,17]. Similar metasomatic processes were observed in the Tamazeght alkaline HFSE/REE-enriched pluton in Morocco [20] and other deposits [2,4,[7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Rare Earth Elements in Mineral Deposits: Speciation in Hydrothermal Fluids and Partitioning in Calcite

Perry

Gysi

2018

Geofluids

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is properly cited.Studying the speciation and mineral-fluid partitioning of the rare earth elements (REE) allows us to delineate the key processes responsible for the formation of economic REE mineral deposits in natural systems. Hydrothermal REE-bearing calcite is typically hosted in carbonatites and alkaline rocks, such as the giant Bayan Obo REE deposit in China and potential REE deposits such as Bear Lodge, WY. The compositions of these hydrothermal veins yield valuable information regarding pressure ( ), temperature ( ), salinity, and other physicochemical conditions under which the REE can be fractionated and concentrated in crustal fluids. This study presents numerical simulation results of the speciation of REE in aqueous NaCl-H 2 O-CO 2 -bearing hydrothermal fluids and a new partitioning model between calcite and fluids at different --conditions. Results show that, in a high CO 2 and low salinity system, bicarbonate/carbonate are the main transporting ligands for the REE, but predominance shifts to chloride complexes in systems with high CO 2 and high salinity. Hydroxyl REE complexes may be important for the solubility and transport of the REE in alkaline fluids. These numerical predictions allow us to make quantitative interpretations of hydrothermal processes in REE mineral deposits, particularly in carbonatites, and show where future experimental work will be essential in improving our modeling capabilities for these ore-forming processes.

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“…Enrichment of HFSE to enhanced grades in alkaline intrusions is generally thought to be caused by magmatic fractionation, but mineralogical and petrologic evidence often points to post-magmatic pneumatolytic or hydrothermal processes. Post-magmatic mineralization events are commonly associated with intensive and highly variable alteration types of both intrusive and wall rocks, thereby superimposing primary petrographic features [1,2,6,[8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Mineralogical and Chemical Characterization of Zr-REE-Nb Ores from Khalzan Buregtei (Mongolia)—Approaches to More Efficient Extraction of Rare Metals from Alkaline Granitoids

et al. 2019

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Alkaline rocks are worldwide observed as hosts for rare metal (Zr-REE-Nb) minerals. The classification of the ore bearing rock type is challenging due to the fact that textures and mineral assemblage are obscured by post-magmatic alteration. In addition, the alteration causes fine and intricate intergrowth of the ore minerals with associated gangue. Hence, intensive comminution is necessary to liberate the ore minerals, which is one parameter hampering the economical use of this deposit type. This study provides a quantitative mineralogical investigation of the ore bearing rock suite at Khalzan Buregtei as an example of rare metal deposits. R1-R2 multication parameters are shown to be highly appropriate as quantitative mineralogical indicators based on readily available major element datasets to visualize and quantify alteration types of the ore bearing rock suite. The ore minerals were found to be associated with a cluster-forming assemblage of post-magmatic phases. Automated mineralogy was applied to quantify the textural properties of the ore mineral clusters. This finding permits efficient pre-concentration of rare metal ore at coarser particle size fraction, requiring less energy consuming comminution.

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Lithogeochemical Vectors for Hydrothermal Processes in the Strange Lake Peralkaline Granitic REE-Zr-Nb Deposit

Cited by 72 publications

References 34 publications

Fluid evolution in the Strange Lake granitic pluton, Canada: Implications for HFSE mobilisation

Fluid evolution in the Strange Lake granitic pluton, Canada: Implications for HFSE mobilisation

Rare Earth Elements in Mineral Deposits: Speciation in Hydrothermal Fluids and Partitioning in Calcite

Mineralogical and Chemical Characterization of Zr-REE-Nb Ores from Khalzan Buregtei (Mongolia)—Approaches to More Efficient Extraction of Rare Metals from Alkaline Granitoids

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