Transfer of deformation during indentation: Inferences from the post- middle Miocene evolution of the Dinarides

Abstract

Understanding the structural and kinematic effects of indentation is still debated due to the large number of competing mechanisms associated with the complex orogenic build-up. Among the many examples available worldwide, the evolution of the Adriatic continental microplate in the Mediterranean domain provides one of the best places to understand the mechanics of indentation. This understanding is hampered by the lack of structural and kinematic data in the Dinarides, an orogen situated at the critical transition between the Alps, Albanides and Hellenides, and across the Adriatic margin of the Apennines. We have studied the less known area of the central and south-eastern Dinarides by focussing on collecting a new kinematic dataset for structures formed during the Adriatic indentation, which postdates the main Late Jurassic – Paleogene orogenic structuration. Our results are in agreement with previous interpretations of an early-middle Miocene period of extension that affected the entire orogen across its strike and is incompatible with indentation effects in the studied parts of the Dinarides. More importantly, we demonstrate for the first time that the post- middle Miocene Dinarides deformation was characterized by a coherent regional system of large offset dextral strike-slip faults, which transfer gradually their offsets to thrusts and high-angle reverse faults. The overall deformation transfer mechanism can be described as a special class of continental restraining bends or stepovers, whose geometry is controlled by rheological distribution. The integration of our results in the larger geodynamic context shows that the post-middle Miocene Dinarides fault system accommodates the differential motion between the N- to NE-wards Adriatic indentation and the rapid S- to SW- ward movement of a Hellenides area situated SE of the Kefalonia Fault, driven by the Aegean slab-roll back.