Role of topography-induced gravitational stresses in basin inversion:: The case study of the Pannonian basin

Numerical stress models suggest that gravitational body forces associated with elevated topography around sedimentary basins can significantly influence the stress and strain pattern in basin interiors. In the absence of tectonic forces, basins surrounded by high-altitude mountain ranges experience net horizontal compression. Owing to gravitational forces pointing from areas of high gravitational potential energy to subsided basin areas, further lithospheric extension can eventually terminate, leading to a gradual late stage inversion of the entire basin system. Modeling results suggest that the state of recent stress in the Pannonian basin, particularly in its western part, is controlled by the interplay of plate boundary forces, i.e., the counterclockwise rotation and northward indentation of the Adriatic microplate against the Alpine-Dinaric belt, and buoyancy forces associated with the elevated topography and related crustal thickness variation of the Alpine-Dinaric belt. Model calculations show that uplifted regions surrounding the basin system can exert compression on the thinned Pannonian lithosphere of similar to 40-60 MPa that is of the order of the assumed far-field tectonic stress magnitudes. The combined analysis of stress sources of tectonic and gravitational origin helps estimating the magnitude of maximum horizontal compression. High levels of compressional stresses (up to >100 MPa) are concentrated in the elastic core of the lithosphere, consistent with the ongoing structural inversion of the Pannonian basin system.