Dumortierite- and corundum-bearing quartz–feldspar–mica rocks of the Belomorian Eclogite Province

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Marco E. Ciriotti
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Dumortierite- and corundum-bearing quartz–feldspar–mica rocks of the Belomorian Eclogite Province

Messaggio da Marco E. Ciriotti » mer 24 gen, 2018 20:28

Referenza:
▪ Dokukina, K.A., Konilov, A.N., Van, K.V., Mints, M.V. (2018): Dumortierite- and Corundum-Bearing Quartz–Feldspar–Mica Rocks of the Belomorian Eclogite Province: An Example of Melting of Phengite + Quartz. Doklady Earth Sciences, 477, 1353-1357.

Abstract:
In the Salma eclogite of the Belomorian eclogite province, a dumortierite–phengite–corundum–bearing quartz–feldspar rock has been studied: its primary HP mineral paragenesis included garnet, phengite, and quartz. The phengite–quartz rocks were formed during dehydration and/or melting of boron-containing rocks when they were dipped in the Meso- Neoarchaean subduction zone to a depth of not less than 70 km. As a result of the subsequent superimposed high-temperature metamorphic events under PT conditions of high-pressure granulite facies, the phengite in quartz underwent incongruent dehydration melting with formation of complex polymineral pseudomorphs, consisting of feldspars, biotite, newly formed muscovite, kyanite, corundum, and dumortierite. New estimates of the metamorphic temperature (850–900°C according to the melting reactions of phengite and the dumortierite field of stability; about 1000°C by the reintegrated composition of feldspar–mesoperthite) that affected the HP parageneses of Salma eclogitized rocks are at least 50–100°C (or even more) higher than them estimated earlier.
Marco E. Ciriotti

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