Age and genesis of Neoachean ruby deposit from Greenland
The Fiskenæsset Complex of Greenland with an inferred metamorphic age of 2.7–2.5 Ga hosts one of the oldest ruby deposits in the world, named Bjørnesund. Although it was discovered at the end of 1970s, the exact time of formation and genesis of this deposit are still poorly known.
Ruby mineralization occurs in mica shists hosted by anorthosites of the Fiskenæsset Complex. In situ SIMS U-Pb dating of rare rutile inclusions within ruby crystals yielded concordant ages averaging 2482 ± 37 Ma (95% confidence; n = 4; mean square of weighted deviates = 0.45), which to the best of our knowledge is the first U-Pb age for rocks from this area. Applied geothermobarometric methods indicated that the formation of ruby-bearing rocks occurred at temperatures of ~710–730°C based on Zr-in-rutile thermometry and at maximum pressure of 400 MPa. Trace element ratios within ruby such as Ga/Mg, Cr/Ga, Fe/Ti, and FeO-Cr2O3-MgO-V2O3 (wt.%) vs. FeO + TiO2 + Ga2O3(wt.%) commonly used as proxies to identify corundum origins correspond to a metamorphic signature. It implies that formation of this ruby deposit may be linked to regional metamorphism during the Neoarchean which overprinted the Fiskenæsset anorthosite complex.
Details
Author
Elena S. Sorokina1, Axel K. Schmitt2, Anette Juul-Nielsen3, Roman E.* Botcharnikov4, Tobias Häger4Institutionen
1Vernadsky Institute of Geochemistry and Analytical Chemistry Russian Academy of Sciences, Moscow, Russian Federation;Institut für Geowissenschaften, Johannes Gutenberg-Universität Mainz (JGU), J.-J.-Becher-Weg 21, 55128 Mainz, Germany; 2John de Laeter Centre, Curtin University, Bentley WA 6102, Australia; 3Government of Greenland, P.O.Box 1015, 3900 Nuuk, Greenland; 4Institut für Geowissenschaften, Johannes Gutenberg-Universität Mainz (JGU), J.-J.-Becher-Weg 21, 55128 Mainz, GermanyVeranstaltung
Geo4Göttingen 2025Datum
2025DOI
10.48380/308j-ep05
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