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@article{1391542,
author = {Belley, P.M. and Dzikowski, T.J. and Fagan, A. and Cempírek, Jan and Groat, L.A. and Mortensen, J.K. and Fayek, M. and Giuliani, G. and Fallick, A.E. and Gertzbein, P.},
article_location = {QUEBEC},
article_number = {4},
doi = {http://dx.doi.org/10.3749/canmin.1700018},
keywords = {sapphire; corundum; marble; calc-silicate rock; scapolite; gem deposits; metamarl; nepheline; proterozoic},
language = {eng},
issn = {0008-4476},
journal = {Canadian Mineralogist},
title = {Origin of scapolite-hosted sapphire (corundum) near Kimmirut, Baffin Island, Nunavut, Canada},
volume = {55},
year = {2017}
}
TY - JOUR
ID - 1391542
AU - Belley, P.M. - Dzikowski, T.J. - Fagan, A. - Cempírek, Jan - Groat, L.A. - Mortensen, J.K. - Fayek, M. - Giuliani, G. - Fallick, A.E. - Gertzbein, P.
PY - 2017
TI - Origin of scapolite-hosted sapphire (corundum) near Kimmirut, Baffin Island, Nunavut, Canada
JF - Canadian Mineralogist
VL - 55
IS - 4
SP - 669-699
EP - 669-699
PB - MINERALOGICAL ASSOC CANADA
SN - 00084476
KW - sapphire
KW - corundum
KW - marble
KW - calc-silicate rock
KW - scapolite
KW - gem deposits
KW - metamarl
KW - nepheline
KW - proterozoic
N2 - Gem-quality corundum (sapphire) occurs in scapolite-rich calc-silicate rock hosted in marble of the Lake Harbour Group near Kimmirut, southern Baffin Island. A deposit of blue and colorless gem corundum (Beluga occurrence) is compared to a similar calc-silicate pod generally lacking corundum but containing nepheline (Bowhead occurrence) and located 170 m to the SSW. Corundum formation was made possible by three equally important sequential metamorphic reactions: (1) formation of nepheline, diopside, and K-feldspar (inferred) at granulite facies peak metamorphic conditions; (2) partial retrograde replacement of the peak assemblage by phlogopite, oligoclase, calcite, and scapolite (Me-50-Me-67) as a result of CO2-, H2O-, Cl-, F-bearing fluid influx at 1782.5 +/- 3.7 Ma (P-T 720 degrees C, 6.2 kbar); and (3) retrograde breakdown of scapolite + nepheline (with CO2-and H2O-bearing fluid) to form albite, muscovite, corundum, and calcite. Late, low-temperature zeolite mineralization is common in corundum-bearing zones. Based on thermodynamic models, the corundum-forming reaction only occurs in a 100 degrees C window with an upper limit determined by scapolite-nepheline stability, and a lower limit determined by the formation of Al-silicate rather than corundum. The protolith is inferred to be dolomitic argillaceous marl with no evidence to suggest the initial presence of evaporites. The enrichment of trace metals V and Cr, and the depletion of Co, Ni, and Mn, suggest reducing diagenetic conditions in the initial sediment. Beluga calc-silicate rock is strongly depleted in REE. Oxy-dravite delta B-11 (+3.9 +/- 0.7%) is consistent with a marine boron source. The oxygen isotope composition of corundum (delta O-18(VSMOW) = 16.4 +/- 0.1%) is comparable to that of corundum in marble or desilicated pegmatite associated with marble.
ER -
BELLEY, P.M., T.J. DZIKOWSKI, A. FAGAN, Jan CEMPÍREK, L.A. GROAT, J.K. MORTENSEN, M. FAYEK, G. GIULIANI, A.E. FALLICK and P. GERTZBEIN. Origin of scapolite-hosted sapphire (corundum) near Kimmirut, Baffin Island, Nunavut, Canada. \textit{Canadian Mineralogist}. QUEBEC: MINERALOGICAL ASSOC CANADA, 2017, vol.~55, No~4, p.~669-699. ISSN~0008-4476. Available from: https://dx.doi.org/10.3749/canmin.1700018.
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