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Two sandstone samples from the upper and lower part of the Ordovician succession of Svoge Unit were analyzed in order to determine their detrital zircon U–Pb age spectra using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). One sample was collected from the Hirnantian siliciclastic glaciomarine deposits of the Sirman Formation. The other sample is amiddle Darriwilian sandstone from the lower half of the Grohoten Formation. Additionally, micropetrographic studies were performed. They are composed predominantly of detrital monocrystalline quartz grains with uniform or rarely undulose extinction and only sporadically presented feldspar grains, muscovite flakes and single rock fragments. The heavy mineral assemblages are also characterized mostly by detrital zircon. As suggested from previous studies of the Hirnantian glaciomarine deposits of Sirman Formation, the provenance of siliciclastic material was most probably associated with sedimentary recycling of maturesands deposited across the North Gondwana Platform. Multi-dimensional scaling statistical technique allowed a reliable objective identification of the potential source areas in Northern Africa and palaeogeographic reconstructions were made. Both samples are close to the Trans-Saharan Belt provenance, which is the most probable source for the detrital component. Our data supportthe idea proposed by previous researchers that the present-day position of some of these terranes implies significant dextral strike-slip displacement, probably due to the movement on the Pangea megashear during the Carboniferous and Permian.

Two sandstone samples from the upper and lower parts of the Ordovician succession of the Svoge Unit were analyzed in order to determine their detrital zircon U-Pb age spectra using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Multi-dimensional scaling statistical technique allowed a reliable objective identification of the potential source areas in North Africa and paleogeographic reconstructions were made. Both samples indicate a close proximity to the Trans-Saharan Belt provenance, which is the most probable source of the detrital component.

Two contrasting Variscan units are juxtaposed in the area of Central Stara Planina Mountain. They are represented by two metamorphic complexes: a high-grade (Central Srednogorie high-grade metamorphic complex -CSHGMC) and low-grade (Stara Planina low-grade metamorphic complex -SPLGMC). Unlike the area to the west (Zlatitsa Stara Planina Mountain), the contact between them is severely overprinted by Palaeocene-Eocene thickskinned thrusting and Miocene-Quaternary extension. The suturing/docking of the two units is well constrained as Visean (∼ 330 Ma) and after a gap of about 15-20 Ma voluminous batches of granite magma were emplaced into the SPLGMC. These granites (Karlovo-Ribaritsa suite) are almost everywhere intensively foliated and they delineate a Late Variscan strike-slip dominated tectonic belt. As a contrast, another widespread granitoid suite (Kalofer granitoids) does not display gneissic fabric and can be regarded as a part of the batholithic-scale, composite Hisarya-Pastrovo pluton (303 ± 3 Ma). Our study documented contacts of the Kalofer granitoid suite, the type of the internal fabric and the presence of inclusions. The perfectly outcropped Palaeogene Botev Vrah allochthon is built by a sill-like body of Kalofer granitoids, emplaced conformably into SPLGMC. These granitoids are foliated along their margins as well as in shear zones. Despite this solid-state overprint, numerous meso-scale features indicate intrusive relations. On the other hand, it is well known that Kalofer granitoids are intrusive into CSHGMC gneisses and they also containThe work on this paper was initiated during the realization of PhD project (Eleonora Balkanska) funded by grant VU-13/06 from the Bulgarian National Science Fund (NSF). Additional support was provided by another NSF grant (DMU-03/41). 709km-scale stopped blocks/rafts from them. These relations undoubtedly indicate that the composite Hisarya-Pastrovo pluton is stitching one of the most important Variscan contacts in the central part of the Balkan peninsula.