Informace o publikaci
Origin of scapolite-hosted sapphire near Kimmirut, Baffin Island, Nunavut, Canada
| Autoři | |
|---|---|
| Rok publikování | 2017 |
| Druh | Článek ve sborníku |
| Konference | MINERAL RESOURCES TO DISCOVER, VOLS 1-4 |
| Fakulta / Pracoviště MU | |
| Citace | |
| Popis | 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 colourless 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; 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. Oxy-dravite 611B is +3.9 +/- 0.7 parts per thousand. The oxygen isotope composition of corundum (delta O-18(VSMOW)) is 16.4 +/- 0.1 parts per thousand. |