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TitleFormation of the Rock Canyon Creek carbonate-hosted REE-F-Ba deposit, British Columbia, Canada: Constraints from Mg-Sr isotopes of dolomite, calcite, and fluorite
 
AuthorAraoka, D; Simandl, G J; Paradis, S; Yoshimura, T; Hoshino, M; Kon, Y
SourceJournal of Geochemical Exploration vol. 240, 107045, 2022 p. 1-15, https://doi.org/10.1016/j.gexplo.2022.107045 Open Access logo Open Access
Image
Year2022
Alt SeriesNatural Resources Canada, Contribution Series 20220212
PublisherElsevier
Documentserial
Lang.English
Mediapaper; digital; on-line
File formatpdf
ProvinceBritish Columbia
Lat/Long WENS-141.4611 -112.8778 60.6483 47.8381
Subjectsgeochemistry; Science and Technology; magnesium; isotopes; strontium; dolomites; calcite; fluorite; carbonate
Illustrationslocation maps; photomicrographs; tables; plots; graphs
ProgramTargeted Geoscience Initiative (TGI-5) Volcanic and sedimentary systems - volcanogenic massive sulphide ore systems
Released2022 06 21
AbstractThe Rock Canyon Creek REE-F-Ba deposit is a carbonate-hosted REE deposit located in the Alkaline Province of British Columbia, Canada, which hosts most REE mineralization. It shares tectonic, stratigraphic and structural similarities with nearby Mississippi Valley-type deposits. To constrain the dolomitization and mineralization processes, the d26Mg, 87Sr/86Sr, and elemental compositions of dolomite, calcite, and fluorite were determined. The d26Mg values of dolomite from the unmineralized zone (- 1.83 per mil and - 1.67 per mil) are consistent with marine evaporative dolomite, but those from the mineralized zone (- 0.97 per mil to - 0.17 per mil) are higher and more variable. The linear 87Sr/86Sr-Sr/Mg relationships, both in the dolomite and calcite from the unmineralized zone, suggest dolomitization in an evaporative marine environment. The high d26Mg values with large variation and the non-stoichiometric Ca/Mg ratios in the dolomite from the mineralized zone suggest that this dolomite interacted with a relatively low-temperature hydrothermal fluid (<200 °C). Considering the Na, Ca, Sr, Ba, and LREE-enrichment and low 87Sr/86Sr signature in the dolomite from the mineralized zone as well as mineral paragenesis in the deposit, the most plausible scenario for the formation of the deposit is that marine-evaporitic dolomite re-equilibrated with basinal fluids along permeable zones, and at a later stage, carbohydrothermal REE-bearing fluids infiltrated into the Rock Canyon Creek brecciated zone and deposited the REE mineralization. Late-stage, post-mineralization calcite veins and iron oxides formed in the upper part of the deposit under supergene conditions, as suggested by combination of textural observations, REE patterns, and differences in isotopic compositions between dolomite and calcite from the mineralized zone. This study demonstrates that d26Mg, 87Sr/86Sr, and element/Mg ratios in carbonate minerals are useful for characterizing mineralizing fluids in carbonate-hosted deposits, and discriminating mineralization-related dolomite from marine evaporative dolomite and unmineralized hydrothermal dolomite.
Summary(Plain Language Summary, not published)
The Rock Canyon Creek rare-earth-fluorite- barite (REE-F-Ba) deposit is a carbonate-hosted REE deposit located in the Alkaline Province of British Columbia, Canada. Elemental compositions of dolomite, calcite, and fluorite and various isotopes (Mg and Sr) were determined to constrain the dolomitization and mineralization processes. Dolomitization occurred in an evaporative marine environment and/or involved a relatively low-temperature hydrothermal fluid (<200 °C). Rare earth elements precipitation formed as the result of interaction of late carbohydrothermal fluids with previously formed hydrothermal dolomite fluids along permeable zones.
GEOSCAN ID330520

 
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