Brittle deformation, palaeostress field reconstruction and tectonic evolution of the Eastern Balkanides (Bulgaria) during Mesozoic and Cenozoic times

Abstract

Brittle tectonics analysis and stress tensor reconstructions allow us to better depict the Mesozoic and Cenozoic geodynamical evolution of the Eastern Balkanides which is characterized by a series of overimposed basin-systems. The Late Permian–Triassic corresponds to a wide carbonate platform with local embryonic troughs. During the Jurassic–Early Cretaceous period, the area, limited by regional unconformities, was at first dominated by the existence of a deep basin until the latest middle Jurassic, then by its gradual closure during the Late Jurassic–Early Cretaceous. Traces of these tectonic events are found as a result of brittle tectonic data analysis, especially in the Strandja Zone where NE–SW extension and ENE–WSW compression may be related to the Early Alpine phases of rifting and shortening, respectively. The Late Cretaceous–middle Eocene period was governed by the back-arc basin/island-arc system of East Balkan/Srednogorie zones. The inversion of these extensional zones occurred after the Maastrichtian, then important shearing and thrusting developed during the major shortening in the latest Middle Eocene. These Late Alpine tectonic phases were well characterized by brittle tectonics and the analysis of faulting in terms of stress tensors allows us to identify the main directions of extension of the rifting stage which is north–south to NNE–SSW, and the directions of compression of the Laramian and Illyrian phases, which are NE–SW and north–south, respectively. The relationships between folding and reverse and strike–slip faults are established as well as the occurrence of post-folding normal faults assigned to collapse process following the shortening.

Lithospheric structure in Central Europe: Integrated geophysical modelling

“…The consequence for such interpretation is that the calculated field does not fit very well with the values extracted from the map of the surface heat flow density (Pollack et al, 1993 Lenkey, 1999) Our models discover some interesting features. They show that the Moesian Platform is overthrust from the North by the Southern Carpathians and from the South by the Balkanides, which had been indicated already earlier based on geological studies (Bergerat et al, 2010;Fügenschuh and Schmid, 2005;Iancu et al, 2005;Rabăgia and Matenco, 1999) (Fig. 28 and Fig.…”

Kinematic reconstructions and magmatic evolution illuminating crustal and mantle dynamics of the eastern Mediterranean region since the late Cretaceous

“…As early as the latest Cretaceous, an inversion of extensional structures occurred throughout the Balkans and the Pontides [Yılmaz et al, 1997;Sunal and Tüysüz, 2002;Bergerat et al, 2010]. The eastern Pontides then underwent a rapid uplift in the Paleocene-early Eocene [Boztuğ et al, 2004].…”

Sedimentary basin tectonics from the Black Sea and Caucasus to the Arabian Platform: introduction

“…These results are comparable to those of the Transcaucasus region to the SE where it seems that a similar tectonic evolution occurred during this period . Metamorphosed rock units related to Cimmerian events are also found in the Strandja unit of Eastern Balkanides (Bergerat et al 2010).…”

“…The extensional events, including the formation of the Black Sea basin, that took place mainly during middle-Late Cretaceous times (Bergerat et al 2010;Kaymakci et al 2010;Khriachtchevskaia et al 2010;Konerding et al 2010) were replaced as subduction terminated in the northern Neotethys and collision of the intervening continental terranes began, leading to inversion tectonics throughout the circum-Black Sea area. The onset of inversion tectonics is fairly precisely dated by structural relationships seen in seismic data on the northern margin of the Black Sea as late Middle Eocene (Khriachtchevskaia et al 2010), following a period of relative quiescence.…”