The geodynamic evolution of retreating subduction boundaries, such as in young and active Mediterranean orogens, is associated with lithospheric removal after the continental collision. This form of tectonic evolution finds application in the Southeast Carpathians where geological, geophysical, and petrological evidence are interpreted for anomalous thermal and topographic transients. A series of numerical geodynamic experiments are conducted to test the evolution of surface topography and crustal thickness induced by lithosphere delamination and potential slab break-off. Our results show that the surface uplift and crustal extension occur due to the dynamic/thermal forcing of the asthenospheric mantle as a response to lithosphere delamination. Moreover, the crustal shortening and subsidence induced by the delaminating lithosphere evolve in a migratory pattern concurrent with the mobilization of the underlying lithosphere. These results are in agreement with the present-day lithospheric structure, topographic transients (i.e., approximately 1 km surface uplift of Carpathians hinterland and the subsidence of the Focsani foredeep basin), as well as the development of extensional Braşov basin and Persani-south Harghita volcanism since 3 Ma. Further, 3-D mantle flow models based on P wave tomography results also predict the mantle upwelling induced dynamic topography (up to 1km) for the Transylvania region (hinterland) and slab pull controlled subsidence in the Foçsani basin. These results emphasize the significant role of lithospheric/mantle dynamics in the Alpine-Mediterranean orogeny where the origin of short-lived geological processes remains enigmatic.
Göğüş, O. H., R. N. Pysklywec, and
C. Faccenna (2016), Postcollisional lithospheric evolution of the Southeast Carpathians: Comparison of geodynamical models and observations, Tectonics, 35, doi:10.1002/2015TC004096.
Uluocak, E. Ş., Pysklywec, R. N., Göğüş, O. H., & Ulugergerli, E. U. (2019). Multidimensional geodynamic modeling in the Southeast Car- pathians: Upper mantle flow-induced surface topography anomalies. Geochemistry, Geophysics, Geosystems, 20, 3134–3149. https://doi. org/10.1029/2019GC008277