@article{fdi:010070893,
  title = {{O}rigin of scapolite-hosted sapphire (corundum) near {K}immirut, {B}affin island, {N}unavut, {C}anada},
  author = {{B}elley, {P}. {M}. and {D}zikowski, {T}. {J}. and {F}agan, {A}. and {C}empirek, {J}. and {G}roat, {L}. {A}. and {M}ortensen, {J}. {K}. and {F}ayek, {M}. and {G}iuliani, {G}aston and {F}allick, {A}. {E}. and {G}ertzbein, {P}.},
  editor = {},
  language = {{ENG}},
  abstract = {{G}em-quality corundum (sapphire) occurs in scapolite-rich calc-silicate rock hosted in marble of the {L}ake {H}arbour {G}roup near {K}immirut, southern {B}affin {I}sland. {A} deposit of blue and colorless gem corundum ({B}eluga occurrence) is compared to a similar calc-silicate pod generally lacking corundum but containing nepheline ({B}owhead occurrence) and located 170 m to the {SSW}. {C}orundum 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 ({M}e-50-{M}e-67) as a result of {CO}2-, {H}2{O}-, {C}l-, {F}-bearing fluid influx at 1782.5 +/- 3.7 {M}a ({P}-{T} < 720 degrees {C}, 6.2 kbar); and (3) retrograde breakdown of scapolite + nepheline (with {CO}2-and {H}2{O}-bearing fluid) to form albite, muscovite, corundum, and calcite. {L}ate, low-temperature zeolite mineralization is common in corundum-bearing zones. {B}ased 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 {A}l-silicate rather than corundum. {T}he protolith is inferred to be dolomitic argillaceous marl with no evidence to suggest the initial presence of evaporites. {T}he enrichment of trace metals {V} and {C}r, and the depletion of {C}o, {N}i, and {M}n, suggest reducing diagenetic conditions in the initial sediment. {B}eluga calc-silicate rock is strongly depleted in {REE} ({T}otal {REE} similar to 18 ppm). {O}xy-dravite delta {B}-11 (+3.9 +/- 0.7%) is consistent with a marine boron source. {T}he 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. {P}hlogopite and muscovite {A}r-40/(39) {A}r ages and calculated closure temperatures (considered estimates) are ca. 1640 {M}a ({T}-c = 455 to 515 degrees {C}) and 1510 {M}a ({T}c = 410 to 425 degrees {C}), respectively. {I}n the {L}ake {H}arbour {G}roup, the most prospective areas for gem corundum exploration are expected to be contiguous to the thrust fault separating the {L}ake {H}arbour {G}roup and {N}arsajuaq terranes, where the retrograde, amphibolite facies overprint of the granulite peak assemblages was most pervasive.},
  keywords = {sapphire ; corundum ; marble ; calc-silicate rock ; scapolite ; gem deposits ; metamarl ; nepheline ; proterozoic ; {CANADA}},
  booktitle = {},
  journal = {{C}anadian {M}ineralogist},
  volume = {55},
  numero = {4},
  pages = {669--699},
  ISSN = {0008-4476},
  year = {2017},
  DOI = {10.3749/canmin.1700018},
  URL = {https://www.documentation.ird.fr/hor/fdi:010070893},
}