The Carpathian–Balkan bends: an oroclinal record of ongoing Arabian–Eurasian collision

Jessica Shaw, and Stephen T. Johnston

The Alpine orogen of southeastern Europe is characterized by two, coupled, highly arcuate segments; a northerly Carpathian segment characterized by a 150 degree, convex to the east arc, and a more southerly, 180 degree convex to the west Balkan segment. Regional paleomagnetic data are neither abundant enough, nor of sufficient quality to fully test the origin of these arcuate segments of the Alpine orogen. However, paleomagnetic studies of Cretaceous – Micoene rocks within the northern, Carpathian segment show significant time progressive clockwise rotations that are consistent with interpretation of the arcuate segments as oroclines that developed due to bending of a previously linear orogen. The Carpathian - Balkan region lies immediately north northeast of an Eastern Mediterranean region within which Late Eocene to Miocene rocks are characterized by anomalously shallow paleomagnetic inclinations. This Eastern Mediterranean Inclination Anomaly requires that the region moved 500 to 1000 km north at roughly the same time as the Carpathian - Balkan bending of the Alpine orogen. A geometrically constrained paleogeographic model shows that northward displacement of the Eastern Mediterranean region, together with an equal amount of westward displacement, can explain the observed Carpathian - Balkan oroclines as buckles of an originally linear orogen that was pinned to the southeast against the northwestwardly migrating East Mediterranean crustal block, and to the northwest against autochthonous Europe. The implied northwestward translation of the Eastern Mediterranean region is consistent with the observed ongoing tectonic escape of the Anatolian - Aegean region out of the Arabian - Eurasian collision zone.