The Outer Carpathian flysch nappes encircle an Intra-Carpathian domain
which can be divided into two megatectonic units (North Pannonian and
Tisza) mostly on the basis of contrasting Mesozoic and Palaeogene
facies development. We see two major kinematic problems to be solved:
(1) The present distribution of the Mesozoic and Palaeogene facies is
mosaic-like, and some belts form exotic bodies within realms of
Austroalpine affinity. (2) Late Eocene palinspastic reconstruction of
the Outer Carpathian flysch nappes suggest, that the entire
Intra-Carpathian area must have been located several hundreds of
kilometres to the south and to the west of its present position.
Neogene extension can account for shortening in the external Carpathian
nappes, but is unable to explain Mesozoic facies anomalies and offsets
of Palaeogene formations. We suggest that evolution of the
Intra-Carpathian area involved first Late Palaeogene-Early Miocene
juxtaposition of the North-Pannonian and Tisza megatectonic units,
accompanied by the closure of the external Carpathian flysch troughs;
thereafter extension of this amalgamated unit occurred, which was
compensated by thrusting of flysch nappes onto the European foreland
and formation of molasse foredeeps.
Eastward escape of the North-Pannonian unit from the Alpine collisional
belt involved left lateral shear along the Pieniny Klippen belt and
right lateral shear along the Mid-Hungarian zone. Parts of the Late
Palaeogene basin and an Early Miocene volcanic edifice were dissected,
offset and elongated by several 100 kms. The driving mechanism of the
eastward escape of the Intra-Carpathian area can be related to the
collision of Apulia and Europe and the subduction of the external
Carpathian crust under the Pannonian units. The escape ceased gradually
in the Early Miocene, when oblique collision between the
North-Pannonian unit and European continent occurred.
Neogene extension of the Pannonian region was an areal deformation. The
extension at locally variable rate resulted in the break-up of the
heterogenous floor of the Neogene basin.
The driving mechanism of basin extension and contemporaneous
compressional deformation of the external Carpathians is thought to be
related to ongoing subduction, involving the marginal part of the
attenuated European continental crust. Tectonic activity in the
Carpathians and basin subsidence and volcanism shifted in time and in
unison from the west toward the east-southeast.