NEOTECTONICS, SEISMOLOGY AND THE MODE OF LATE CENOZOIC CRUSTAL DEFORMATION IN THE ALBANIDES, BALKAN PENINSULA

The Albanides in the Balkan Peninsula are divided into several tectonic domains displaying different deformation styles & seismic patterns. The External domain (ED), including Paleogene & younger units of the Krasta–Çukali and other tectonic zones to the west, has been affected by compression, manifested in west-directed folds, thrust faults & oblique strike-slip fault systems. The Internal domain (ID) to the east consists of Paleozoic-Mesozoic rocks and Paleogene-Quaternary basinal strata that have been cut by Pliocene & younger normal and transtensional dextral strike-slip faults. Compressional & extensional tectonic regimes in ED and ID are controlled by ~NNW-running fault systems, defining several longitudinal seismogenic zones. The Ionian–Adriatic thrust fault zone in the west includes the northern segment of the Kruja subzone of pure compressional thrust faults, the central segment of the NNW-striking oblique thrust faults of the Peri-Adriatic foredeep, and the southern segment of the NW-striking, pure-compressional thrust faults in the Ionian zone. The other NW-trending longitudinal seismogenic zones within ID are represented by the Shkodra–Mati–Librazhdi & the Peshkopi–Korçe normal fault systems, forming grabens & half-grabens. Two NE-SW-running transversal zones, Shkodra–Tropoja fault system in the north and the Vlore-Elbasani–Dibra fault zone in the south, transect these longitudinal zones at high angles. Main seismic events of the last 100 years with magnitudes less than Ms=7.0 have been confined mainly to the Ionian–Adriatic thrust fault zone, the Peshkopi–Korçe normal fault system, and the Vlore–Elbasani–Dibra transversal fault zone. Compressional deformation in ED is a result of ongoing oblique collision between Apulia & Eurasia and has been propagating W into the Adriatic depression as evidenced by the seismic profiles. The NE-trending transversal zones facilitate strain partitioning within & between the longitudinal zones and locally coincide with basement structures. Extensional deformation in ID is mainly a tectonic response of the orogenic crust to broad dextral transtension, partitioned into normal & oblique fault systems; NW propagation of crustal stretching from the Aegean extensional province across the Hellenic Peninsula may also be partly responsible for it.