Formation conditions of Upper Eocene olistostromes and retro-overthrusts at the southern slope of the Greater Caucasus

Abstract

The paper considers age, formation conditions, and tectonic setting of Upper Eocene olistostromes of the southern slope of the Greater Caucasus. The formation of olistostromes resulted from the contribution of coarse-clastic material to the Late Eocene basin, which was related to the erosion of thrusted sheets of the Racha–Vandam cordillera of the Gagra–Java zone of the southern slope of the Greater Caucasus and concomitant multiple catastrophic landslide processes. In the Early Pliocene (Rodanian folding phase), Upper Eocene olistostromes along with nappes of the flysch zone were thrust to the south. In the pre- Quaternary (Valakh) folding phase, due to intense shortening, olistostromes in the frontal part of nappes were squeezed, displaced to the north, and thrust with the formation of retro-overthrust, fragments of which remain as isolated blocks (klippen) inside the flysch zone.