Authors / CoAuthors
Bastrakov, E. | Migdisov, A.A. | Huston, D.
Abstract
<div>Heavy rare earth elements are essential in renewable energy and high-tech products. Some natural rare earth element (REE) deposits exhibit heavy rare earth element (HREE) enrichment from < 10% to ~85% of the REE budget (Williams-Jones et al., 2015). </div><div><br></div><div>Controls on REE fractionation in hydrothermal systems are imposed by (1) changes in the relative stability of REE aqueous complexes with temperature (Migdisov et al., 2016) and (2) incorporation or rejection of REE by crystalline structures. Also, the REEs are invariably found as solid solutions but not as pure minerals. REE and yttrium (Y) sulphate complexes are some of the most stable REE and Y aqueous species in hydrothermal fluids (Migdisov and William-Jones, 2008, 2016; Guan et al., 2022) and may be responsible for REE transport and deposition in sediment-hosted deposits. Within the unconformity-related deposits, REEs are hosted mostly by xenotime ((Y,Dy,Er,Tb,Yb)PO4) and minor florencite ((La,Ce)Al3(PO4)2(OH)6) (Nazari-Dehkordi et al., 2019). Modelling the stability of xenotime in the H-O-Cl-(±F)-S-P aqueous system is critical for understanding HREE enrichment in this mineral system.</div><div><br></div><div>We use a newly derived thermodynamic dataset depos for REESO4+ and REE(SO4)2‑ aqueous complexes to generate stability diagrams illustrating mechanisms of REE transport and deposition in the above deposits. Sulphate REE complexes may dominate even in chloride-rich brines and facilitate REE mobilization in acid oxidizing environments. Previously Nazari-Dehkordi et al. (2019) proposed an ore genesis model involving the mixing of discrete hydrothermal fluids that separately carried REE + yttrium and phosphorus. The speciation model that includes sulphate complexes expands this scenario; a process resulting in fluid neutralization or reduction will also promote precipitation of xenotime enriched in HREEs. </div><div><br></div>This Abstract was submitted/presented to the 2022 Specialist Group in Geochemistry, Mineralogy and Petrology (SGGMP) Conference 7-11 November (https://gsasggmp.wixsite.com/home/biennial-conference-2021)
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document
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147239
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Keywords
- ( Project )
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- Critical minerals
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- Geochemistry
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- REE
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- mineralisation
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- EFTF – Exploring For The Future
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- EFTF
- theme.ANZRC Fields of Research.rdf
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- Inorganic Geochemistry
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- Published_External
Publication Date
2023-02-20T02:27:28
Creation Date
2022-09-17T02:00:00
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completed
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An abstract for the Specialist Group in Geochemistry, Mineralogy & Petrology (SGGMP) Biennial conference 2022
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geoscientificInformation
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Specialist Group in Geochemistry, Mineralogy and Petrology (SGGMP) Conference 7-11 November 2022 Yallingup WA
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<div>An abstract for the Specialist Group in Geochemistry, Mineralogy & Petrology (SGGMP) Biennial conference 2022. Based on the published experimental data (by 2022) and correlation algorithms, the authors have derived a dataset of the MHKF equation of state parameters for REESO4+ and REE(SO4)2‑ aqueous complexes. These parameters allow calculations of REE transport and deposition within a wide range of crustal temperatures and pressures (1 to 1000°C and 1 to 5,000 bar). The authors use this dataset to generate stability diagrams illustrating mechanisms of REE transport and deposition in the unconformity-related REE deposits deposits. </div>
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[-54.75, -9.2402, 112.92, 159.11]
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