J 2023

Corundum genesis at the Blue Jay Sapphire occurrence (British Columbia, Canada) as a record of metamorphism and partial melting in the Monashee Complex

ABDALE, Lindsey, Philippe M. BELLEY, Lee A. GROAT, Jan CEMPÍREK, Radek ŠKODA et. al.

Základní údaje

Originální název

Corundum genesis at the Blue Jay Sapphire occurrence (British Columbia, Canada) as a record of metamorphism and partial melting in the Monashee Complex

Autoři

ABDALE, Lindsey (garant), Philippe M. BELLEY, Lee A. GROAT, Jan CEMPÍREK (203 Česká republika, domácí), Radek ŠKODA (203 Česká republika, domácí) a Corey WALL

Vydání

Lithos, Elsevier B.V. 2023, 0024-4937

Další údaje

Jazyk

angličtina

Typ výsledku

Článek v odborném periodiku

Obor

10504 Mineralogy

Stát vydavatele

Nizozemské království

Utajení

není předmětem státního či obchodního tajemství

Odkazy

Impakt faktor

Impact factor: 3.500 v roce 2022

Kód RIV

RIV/00216224:14310/23:00130188

Organizační jednotka

Přírodovědecká fakulta

UT WoS

001012193500001

Klíčová slova anglicky

Corundum; Muscovite; Leucosome; Metamorphic core complex; Partial melting; Metamorphism

Štítky

Příznaky

Mezinárodní význam, Recenzováno
Změněno: 9. 8. 2023 11:37, Mgr. Marie Šípková, DiS.

Anotace

V originále

The sapphire (corundum) occurrence near Revelstoke, British Columbia, Canada, occurs in the Monashee Complex of the Omineca Belt of the Canadian Cordillera. Corundum occurs in boudins or pod-like zones of restite within a garnet-bearing leucosome. Both zones are peraluminous and contain plagioclase, K-feldspar, and biotite and muscovite as the dominant mineral phases. Relative to the leucosome, the corundum-pods are slightly depleted in SiO2 (55.28 wt% in corundum-pods vs. 62.7 wt% in leucosome) and K2O (4.74/7.05 wt%) and enriched in Al2O3 (22.57/21.97 wt%), Fe2O3 (5.96/2.11 wt%), TiO2 (0.71/0.21 wt%), CaO (0.68/0.60 wt%), and MgO (0.59/0.28 wt%). The peraluminous nature of the corundum-bearing pods is consistent with partial melting of a metapelitic protolith. Similar chemical compositions between the corundum-pods and garnet-leucosome are interpreted to infer a single, in situ partial melting event. Coinciding melt-compatible and incompatible elements suggest a closed system. Igneous textures in thin section (coarse-grained, euhedral corundum; twinning in plagioclase; small cuspate-shaped biotite, and myrmekitic intergrowths of feldspars) confirm a partial melt origin. Petrography and thermodynamic models reveal that corundum growth and partial melting was fueled by the breakdown of muscovite along the prograde P-T path. Whole-rock geochemistry of the leucosome groundmass devoid of garnet shows high Sr/Y and La/Yb ratios indicative of garnet fractionation, and garnet mineral chemistry are Ca-poor indicating garnets crystallized from the peraluminous partial melts at peak P-T conditions. 206Pb/238U ages of garnet-equilibrated zircon indicate that peak metamorphic conditions occurred at or before ∼60.69 Ma. Continued zircon growth until 50.22 Ma tracks the presence of continued partial melt following peak metamorphism during nearly-isothermal decompression. A resulting P-T-t path for basement rocks form the Thor-Odin dome constrains the timing of peak metamorphism and ensuing partial melting events during Cordilleran orogenesis.