Paleogene deformation pattern and Neogene post-collisional reorganization of the Dinarides fold and thrust belt

The Late Cretaceous collision of the Adriatic microplate with Eurasia resulted in an overall SW-vergent and in-sequence structural architecture of the Dinarides. In the Paleogene the deformation propagated from the Internal towards the External Dinarides, associated with ca. 130 km of crustal shortening. Fault kinematic data and balanced cross-sections across the External Dinarides suggest contrasting styles along-strike the orogen, separated by a ca. 250 km long dextral transpressive fault. This fault delimits the southern, SW-vergent nappe stack segment from a northern, NE-vergent backthrust-dominated Velebit segment. Based on the distribution of the flexural foreland basin sediments, it is known that these two domains deformed contemporaneously, which marked the end of the Paleogene Dinaric orogeny.

Within these Eo- to early Oligocene syntectonic and older Mesozoic carbonate platform rocks horizontal marine terraces are preserved at elevations of up to 600 m. We extracted terrace surfaces along the entire Adriatic coast from DEMs. All these flat surfaces are degradational, not related to bedding or faults, and they are located on the western side of the main drainage divide facing the Adriatic Sea. Their spatial correlation is in agreement with the position of a reported negative P-wave tomography anomaly, which in turn correlates with the thinned part of the Adriatic lithosphere. Our findings suggest an orogen-wide surface uplift affecting the Dinarides in the Neogene due to mantle delamination.

Our overarching results show that the Paleogene Dinaric orogeny was related to high crustal shorten- and thickening, whereas the Neogene was related mainly to surface uplift.