Gutâi Mts., part of inner Carpathians volcanic arc, consist of products of felsic and intermediate volcanism. The previously known “Badenian Rhyodacitic Formation”, expression of the felsic explosive volcanism, is composed of a well-defined basal unit of ignimbrites, overlain by a sequence of resedimented volcaniclastics of similar origin, interlayered with mudstones. The petrography of ignimbrites shows matrix-supported lapilli tuffs having a heterogeneous composition with insignificant lateral variations. The juvenile components, pumice, glass shards and crystals of plagioclase, quartz and biotite are predominant; cognate nonvesicular glassy clasts are rare, unlike accidental clasts of sedimentary and metamorphic rocks which are abundant. Pyroxene andesite accidental lithic clasts and pyroxene crystal clasts are scarce. The geochemical study of ignimbrites pointed out their rhyolitic character and geochemical signatures resembling subduction-related volcanics. Petrogenesis of ignimbrites involves complex evolution in the crustal magma chamber of some enriched (by subduction components) mantle melts. Magmagenesis could be related to the uprise of the astenospheric mantle during the back-arc opening of the Intracarpathian region.
Fülöp, Alexandrina and Kovacs, Marinel
Petrology of Badenian ignimbrites, Gutai Mts. (Eastern Carpathians),
Studia UBB Geologia
Available at: http://scholarcommons.usf.edu/geologia/vol48/iss1/art2