Present geodynamics of the northern Adriatic plate

Abstract

The northern Adriatic plate is surrounded and squeezed by three orogens (i.e. Apennines, Alps and Dinarides). Therefore, in the same area, the effects of three independent subduction zones coexist and overlap. This supports the evidence that plate boundaries are passive features. The northeastward migration of the Apennines subduction hinge determines the present-day faster subsidence rate in the western side of the northern Adriatic (>1 mm/yr). This is recorded also by the dip of the foreland regional monocline, and the increase SW-ward of the depth of the Tyrrhenian layer, as well as the increase in thickness of the Pliocene and Pleistocene sediments. These data indicate the dominant influence of the Apennines subduction and the related asymmetric subsidence in the northern Adriatic realm. The Dinarides front has been subsided by the Apennines subduction hinge, as shown by the eroded Dalmatian anticlines in the eastern Adriatic Sea. GPS data show the horizontal pattern of motion along the front of the three belts surrounding the northern Adriatic plate. Values of shortening along the prisms are in the order of 2-3 mm/yr (Northern Apennines), 1-2 mm/yr (Southern Alps) and <1mm/yr (Dinarides). The pattern of the new GPS velocities relative to Eurasia account for different tectonic domains and the estimated strain rates are within 0.1 μstrain/yr. The shortening directions tend to be perpendicular to the thrust belt fronts, as expected. The areas where the strain rate sharply decreases across a tectonic feature (e.g., the Ferrara salient) are considered structures seismically loading the brittle layer