Pre-Paleogene Alpine tectonics in Southwestern Bulgaria

Abstract

The pre-Palaeogene Alpine structure of SW Bulgaria consists of the Srednogorie, Morava, Struma and Rhodope Superunits and the Ograzhden Unit. They are characterized by different pre-Alpine and Mesozoic histories. The Mid-Cretaceous and Late Cretaceous thrusts and thrust structure are discordantly and obliquely superimposed over the pre-existing (Triassic and Jurassic – Early Cretaceous) structural and sedimentation environments. The boundaries between the tectonic units are thrust surfaces and zones often hidden by intersecting younger normal faults or/and stitching intrusive bodies or sealed by Palaeogene and Neogene sedimentary formations.