Metacarbonate-hosted Spinel On Baffin Island, Nunavut, Canada: Insights Into the Origin of Gem Spinel and Cobalt-Blue Spinel
Notice bibliographique
Résumé
Research Article| March 01, 2019 Metacarbonate-hosted Spinel On Baffin Island, Nunavut, Canada: Insights Into the Origin of Gem Spinel and Cobalt-Blue Spinel Philippe M. Belley; Philippe M. Belley § Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 6339 Stores Road, Vancouver, British Columbia, Canada V6T 1Z4 § Corresponding author e-mail address: phil.belley@gmail.com Search for other works by this author on: GSW Google Scholar Lee A. Groat Lee A. Groat Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 6339 Stores Road, Vancouver, British Columbia, Canada V6T 1Z4 Search for other works by this author on: GSW Google Scholar Author and Article Information Philippe M. Belley § Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 6339 Stores Road, Vancouver, British Columbia, Canada V6T 1Z4 Lee A. Groat Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 6339 Stores Road, Vancouver, British Columbia, Canada V6T 1Z4 § Corresponding author e-mail address: phil.belley@gmail.com Publisher: Mineralogical Association of Canada First Online: 26 Mar 2019 Online Issn: 1499-1276 Print Issn: 0008-4476 © 2019 Mineralogical Association of Canada The Canadian Mineralogist (2019) 57 (2): 147–200. https://doi.org/10.3749/canmin.1800060 Article history First Online: 26 Mar 2019 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Philippe M. Belley, Lee A. Groat; Metacarbonate-hosted Spinel On Baffin Island, Nunavut, Canada: Insights Into the Origin of Gem Spinel and Cobalt-Blue Spinel. The Canadian Mineralogist 2019;; 57 (2): 147–200. doi: https://doi.org/10.3749/canmin.1800060 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyThe Canadian Mineralogist Search Advanced Search Abstract Samples from 14 spinel occurrences in the Lake Harbour Group (LHG), Baffin Island, Nunavut, Canada, were studied using a combination of petrography, whole rock geochemistry, microprobe analysis, and, where possible, geochronology. Spinel at most occurrences is blue to violet and generally not of gem quality. Two spinel occurrences near Kimmirut contain vivid blue, cobalt-enriched (0.03–0.07 wt.% CoO) spinel. The spinel mostly occurs in metasedimentary (sensu stricto) rocks, with the exception of a few metasomatic occurrences. All spinel occurs in marble and calc-silicate/silicate-rich metacarbonate rocks. Minerals occurring with spinel as part of a stable assemblage include calcite, dolomite, phlogopite, pargasite, diopside, humite, forsterite, scapolite, anorthite, graphite, and pyrrhotite. The spinel formed under peak granulite facies metamorphic conditions.Metasedimentary (s.s.) spinel-bearing rocks in the LHG are interpreted to have the following protoliths: (1) impure dolomite-bearing and dolomitic limestone; (2) dolomitic marl; and (3) evaporitic magnesitic marl. Other significant gemstone occurrences in the LHG (sapphire and lapis lazuli) are interpreted to have similar protoliths. Factors that favor spinel genesis in Mg-bearing metacarbonates include: (1) a low abundance of Si relative to Al, which is a primary control on whether spinel forms in most calc-silicate rocks; (2) low K activity limiting the formation of phlogopite and thus leaving Al available for spinel formation; (3) low XCO2 in marbles; and (4) insufficient quantities of Mg or dolomite reactant in diopsidite limiting Al incorporation into phlogopite to form spinel.The spatial distribution of Co enrichment at the cobalt-blue spinel occurrences is indicative of highly localized enrichment. Cobalt and Ni are interpreted to have been enriched in the original sediment, or during diagenesis or low-grade metamorphism. Concentrations of Co (up to 29 μg/g) and Ni are anomalously high, while concentrations of Fe, Mn, V, Cr, and Cu are much lower than expected; this chemical signature speculatively could be caused by diagenetic processes prior to metamorphism.Pyrrhotite strongly partitions Fe relative to spinel, and therefore an abundance of sulfide is expected to improve the attractiveness (and commercial value) of spinel by decreasing the amount of Fe incorporated, thus preventing spinel from having an overly dark color. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,003 | 0,006 |
| Études des sciences et des technologies | 0,010 | 0,003 |
| Communication savante | 0,003 | 0,001 |
| Science ouverte | 0,002 | 0,002 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,009 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».