| Title | Formation and preservation of brucite and awaruite in serpentinized and tectonized mantle in central British Columbia: implications for carbon mineralization and nickel mining |
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| Author | Steinthorsdottir, K; Dipple, G M; Cutts, J A; Turvey, C C; Milidragovic, D ; Peacock, S M |
| Source | Journal of Petrology vol. 63, no. 11, 2022 p. 1-25, https://doi.org/10.1093/petrology/egac100  Open Access |
| Image |  |
| Year | 2022 |
| Alt Series | Natural Resources Canada, Contribution Series 20220359 |
| Publisher | Oxford University Press |
| Document | serial |
| Lang. | English |
| Media | paper; digital; on-line |
| File format | pdf |
| Province | British Columbia |
| NTS | 93K |
| Area | Australia; Italy |
| Lat/Long WENS | -126.0000 -124.0000 54.0000 53.0000 |
| Subjects | mineralogy; igneous and metamorphic petrology; geochemistry; serpentine; carbon; brucite; nickel; mineral deposits; awaruite |
| Illustrations | location maps; tables; plots; photomicrographs; schematic diagrams |
| Released | 2022 11 03 |
| Abstract | The serpentinized and tectonized mantle in the Decar area in central British Columbia, including rocks which host the Baptiste Ni Deposit, consists of several ultramafic protolith lithologies that are
variably altered to serpentinite, ophicarbonate, soapstone and listvenite. Alteration minerals include brucite (Mg[OH]2), which can be used to sequester atmospheric CO2 and awaruite (Ni3Fe), which is an economically attractive nickel alloy. This
study examines the formation and preservation of brucite (up to 13 wt.%) and awaruite (up to 0.2 wt.%) in the Decar area and demonstrates that both minerals are formed during serpentinization and destroyed during carbonate alteration of mantle rocks.
We distinguish five alteration stages that occurred primarily in a continental environment: 1) low-temperature lizardite serpentinization from meteoric fluids at <300 °C, 2) high-temperature antigorite (±metamorphic olivine) serpentinization from
metamorphic fluids at >300 °C, 3) carbonate alteration, 4) chrysotile veining (±antigorite) serpentinization, and 5) later carbonate alteration from crustal fluids. Brucite formed primarily during late lizardite serpentinization and is most abundant
in rocks that originally had high olivine-pyroxene ratios. Awaruite formed during both late lizardite serpentinization and during antigorite serpentinization and is most abundant in serpentinized olivine-rich harzburgite. The stability and abundance
of brucite and awaruite are controlled by both the host rock composition and degree of serpentinization. The coexistence of brucite and awaruite reflects formation in serpentinized olivine-rich peridotite, and creates an opportunity for
carbon-neutral nickel mining. |
| Summary | (Plain Language Summary, not published)
British Columbia contains extensive volumes of serpentinized (hydrothermally altered) ultramafic rock that have potential for both nickel mining and
carbon dioxide (CO2) sequestration through permanent conversion of Mg-rich silicates into Mg-rich carbonate minerals. Mineable nickel is principally hosted within mineral awaruite (Ni3Fe), whereas the potential for CO2 sequestration is related to the
abundance of mineral brucite (Mg(OH)2). This paper uses the Decar deposit in central British Columbia to study the role of: 1) primary mineralogy of different ultramafic lithologies and 2) hydrothermal alteration on the formation of awaruite and
brucite. The development of critical metal mines (e.g., Ni) with a high capacity for carbon dioxide mineralization represents an opportunity to decarbonize supply chains for renewable energy and reduce the greenhouse gas footprint of resource
development in British Columbia. |
| GEOSCAN ID | 330898 |
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