Late orogenic magmatism and sedimentation within Late Carboniferous to Early Permian basins in the Balkan terrane (Bulgaria): geodynamic implications

The orogenic Balkanid belt, which developed
between the Moesian Plate and the Moravian-Rhodopi-
Thracian Massifs, was affected by the Late Carboniferous
and Early Permian opening of W-E oriented graben
structures. The progressive tectonic rejuvenation of the
basins is demonstrated by the deposition of repeated regional
sedimentary cycles, associated with volcanism that
was mostly localised along the tectonic boundaries, in an
intramontane setting.
The Late Carboniferous volcanism is represented by
rhyodacitic explosive products and hyaloclastites, and by
andesitic flows. During the Early Permian, subvolcanic
rhyodacitic and rhyolitic bodies and the explosive products
prevailed in the western sectors, whereas rhyolitic
ignimbrites occur to the east.
The tectonically active basins are interpreted due to
late orogenic collapse, and the alternation of extensional
tectonics and minor compressional phases is consistent
with the regional transtensional regime, active along the
Variscan suture of Pangaea. The volcanic activity associated
with the evolution of the basins matches the petrogenetic
features and the evolution from early dacitic –
andesitic to late rhyolitic activity in the Southern European
segment of the Variscan system.
These Late Carboniferous-Early Permian sedimentary
and tectono-magmatic events in Bulgaria are characterized,
and compared with the homologous Permo-Carboniferous
sequences along some western European segments
of the Variscan belt.