Significance of Late Permian-Triassic facies zones in terrane reconstructions in the Alpine-North Pannonian domain

Abstract

The present-day setting of the tectonic units (terranes) making up the pre-Neogene basement of the Pannonian Basin and the West Carpathians is the result of large-scale displacements during the Alpine collisional phases. To explain this setting, based on various concepts, a number of models have been proposed in the last decade. Most of them agree in an eastward escape of the “North Pannonian terrane” from the Alpine domain towards the Pannonian during the Palaeogene-Early Miocene period.In the present paper a reconstruction of the pre-escape setting of the displaced terranes is presented based on facies zones in selected time-slices from the Late Permian to the Late Triassic. According to our reconstruction the Inner West Carpathian units were located east of the Austroalpine units forming the northern shelf of the “Euhallstatt”-Meliatic basin of the Vardar oceanic branch. The Drauzug should have been located in a position much more external than its present-day setting. The Transdanubian Range was situated in the northern neighbourhood of the Southern Alps, whereas the Bükk may have been located adjacent to the NW Dinarides. The Mid-Transdanubian zone is a major shear-zone containing elements of the Julian Alps and Sava folds nappe system and the Inner Dinaric ophiolitic melange.Although the nappe-tectonism may have played an important role in the structural evolution of the “North Pannonian terrane”, this mechanism alone can hardly produce hundreds of kilometres of facies offset on the opposite sides of strike-slip zones.