Richter, L, Diamond, LW, Atanasova, P et al. (2 more authors) (2018) Hydrothermal formation of heavy rare earth element (HREE)– xenotime deposits at 100 °C in a sedimentary basin. Geology, 26 (3). pp. 263-266. ISSN 0091-7613
Abstract
Most rare earth element deposits form from magmatic fluids, but there have also been discoveries of heavy rare earth element (HREE)– enriched hydrothermal xenotime deposits within sedimentary basins. As xenotime is notoriously insoluble, the question arises as to whether these lesser-known deposits form at typical basin temperatures or by influx of much hotter magmatic-hydrothermal fluids. The Browns Range District in northern Western Australia hosts deposits of xenotime that are enriched in HREEs and also uranium. The ore bodies consist of fault-controlled hydrothermal quartz-xenotime breccias that crosscut Archean basement rocks and overlying Paleoproterozoic sandstones. Analyses of fluid inclusions show that the xenotime precipitated at remarkably low temperatures, between 100 and 120 °C, in response to decompression boiling. The inclusions contain high excess concentrations of yttrium (10−3 mol/kg), REEs (1–7 × 10−5 mol/kg), and uranium (4 × 10−5 mol/kg) in equilibrium with xenotime at these low temperatures, showing that availability of phosphate limited the amount of xenotime precipitated. The analyses further identify SO4 2– and Cl– as the ligands that facilitated the elevated REE and uranium solubilities. These findings establish that significant REE transport and deposition is feasible at basin temperatures, and hence they raise the potential of unconformity settings for REE exploration. Moreover, the aqueous metal contents support a genetic link between this type of ore fluid and world-class Proterozoic unconformity-related uranium deposits elsewhere.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Funding Information: | Funder Grant number NERC NE/M01147X/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 26 Feb 2018 16:15 |
Last Modified: | 06 Jul 2018 10:19 |
Status: | Published |
Publisher: | Geological Society of America |
Identification Number: | 10.1130/G39871.1 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:127828 |