Gravity constraints on the crustal structure and slab evolution along a transcarpathian transect

Abstract

A new, unified Bouguer anomaly map of the Carpathian arc and the Pannonian basin has been compiled from previously prepared and recently published gravity maps. In order to constrain the crustal structure and the tectonic evolution of the area, a two-dimensional gravity model is presented along a Western Carpathians-Pannonian basin-Southern Carpathians transect. The model is based on deep seismic lines, where available, and on detailed geological sections. The results confirm that the extensional crustal structure of the Pannonian basin revealed by deep seismic surveys agrees with the gravity data. Furthermore, they suggest that the Western and Southern Carpathians area at different stages of their evolution: the subducted oceanic slab under the Western Carpathians has already been assimilated to the asthenosphere, while a crustal slab is still present under the Southern Carpathians. These findings are compatible with the observation that the last major phase of crustal shortening terminated at the early Middle Miocene in the Western Carpathians, but continued throughout the Pliocene in the Southern Carpathians.