Late Variscan ultramylonite from the Moragy Hills, SE Mecsek Mts., Hungary

Gy Lelkes-Felvari, W. Frank, P. Árkai, G. Nagy

Research output: Article

12 Citations (Scopus)

Abstract

A regional shear zone developed during a late stage of the Variscan orogeny in the Moragy Hills, SE Mecsek Mts., Tisza Unit, Hungary. This shear zone brought in contact a Variscan granite suite of Moldanubian lithological affinity (Moragy Granitoid) and a regional metamorphic series (Ofalu series) in which different lithologies with various metamorphic grades are interlaced, displaying a broad range of deformational microtextures. Polyphase garnet-bearing ultramylonites are for the first time petrologically described from this shear zone. Splintery cores of idioblastic garnets are interpreted as relic porphyroclasts from precursor gneiss. Their strongly varying chemical composition indicates amphibolite facies conditions for the parent rock. A new idioblastic garnet generation around these cores reflects compositional growth zoning with a contrasting, homogeneous chemistry pointing to equilibrium conditions. Mineral parageneses and thermobarometric calculations indicate 5.7-6.3 kbar and 450°C peak postkinematic conditions. According to the 40Ar/39Ar analyses on whole rock and biotite-rich concentrates this shearing event took place between 3030 Ma (maximum age) and 270 Ma.

Original languageEnglish
Pages (from-to)65-84
Number of pages20
JournalActa Geologica Hungarica
Volume43
Issue number1
Publication statusPublished - 2000

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Hercynian orogeny
shear zone
garnet
paragenesis
granitoid
amphibolite facies
rock
gneiss
zoning
biotite
lithology
granite
chemical composition
mineral

ASJC Scopus subject areas

  • Geology

Cite this

Late Variscan ultramylonite from the Moragy Hills, SE Mecsek Mts., Hungary. / Lelkes-Felvari, Gy; Frank, W.; Árkai, P.; Nagy, G.

In: Acta Geologica Hungarica, Vol. 43, No. 1, 2000, p. 65-84.

Research output: Article

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KW - Thermobarometry

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