Abstract: Neogene dynamics of the Carpathians: Subduction rollback-related deformation of the upper crust

SPERNER, BLANKA; RADU GIRBACEA; FRANZ MOSER; and PETER ZWEIGEL

The Miocene tectonic evolution of the Carpathians is controlled by a retreating subduction zone beneath their northern and eastern margins. Segmentation of the subducted slab into two parts facilitated differential movements between the two microcontinents in the Inner Carpathian realm, the North Pannonian Block (NPB) and the Tisza-Dacia Block (TDB).

Deformation of the NPB in Lower and early Middle Miocene was influenced by both southwestward subduction below its northeastern margin and eastward lateral extrusion from the Eastern Alps. This resulted in large-scale mass transfer towards the NE, along sinistral strike-slip faults, and was accompanied by counterclockwise rotation of the NPB. Simultaneously, the TDB rotated clockwise around the northwestern corner of the Moesian Platform, causingdextral transpression in the Southern Carpathians and frontal shortening in the Eastern Carpathians. Shortening in the Outer Carpathians was partly compensated by backarc extension in the Pannonian Basin.

In Middle Miocene convergence between the NPB and the European foreland ended and was followed by slab detachment. The rest of the subduction zone beneath the eastern margin of the TDB underwent accelerated rollback due to its reduced width. This resulted in further eastward movement of the TDB accompanied by continued deformation at its southern and eastern margin. Further slab segmentation, caused by the steepening of the subduction zone and southeastward propagating detachment, led to a final narrow slab remaining beneath the Vrancea Zone. Its continued subduction and subsequent detachment were responsible for Quaternary basin formation in the southeastern corner of the Carpathian arc.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria