Известия высших учебных заведений: Геология и разведка (Apr 2017)

THE ISLAND ARC FERROCORDIERITE-ALMANDINE PLAGIORHYOLITES OF THE MOUNT KASTEL, MOUNTAIN CRIMEA

  • E. M. Spiridonov

DOI
https://doi.org/10.32454/0016-7762-2017-2-15-21
Journal volume & issue
Vol. 0, no. 2
pp. 15 – 21

Abstract

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Plagio rhyolites of the Pre-Late Jurassic dyke contain restitegamet (cribrate inter grow ths of almandinespessartine and quartz) and ferrocordierite. The garnets of such habit and composition and with such kind of zonality - the content of Mg increases and the content of Mn decreases from the center to the edges - are typical for ferriferous metapelites of amphibotite facies. Composition of the rocks, during palingenesis of which the melt of plagiorhyolites of the Mount Kastel formed, probably corresponded to the cordierite-almandine plagiogneisses. An assessment of the parameters of these metamorphic rocks forming according garnet and cordierite compositions is »550° С and 4 kbar, so they are metamorphic rocks of the amphibotite facies of moderate pressure. There is an assumption, that Mountain Crime a tectonic zone was possibly formed on the ancient crystalline basement, on the mature continental crust, possible continuation of the structures of Russian Plattorm to the south. Ferro cordierite - sekaninaite has been described in Crimea for the first time. A part of garnet and cordiertte was replaced by highly ferriferous chlorite (daphnite) and pumpellyite-(Fe), a part of biotite, titanomagnetite and ilmenite - by chlorite, epidote, pumpellyite-(Fe) and mineral with intermediate compotition between titantte and vuagnatite. The reby, plagio rhyoltes were subj ected by metamorphism of prehnite-pumpellyite facies.

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