The effect of Triassic basin geometry and lateral facies changes on the Eoalpine deformation of the Balaton Highland and the Veszprém Plateau (Transdanubian Range, Hungary)

Abstract

In this study, we describe the influence of the Triassic basin geometry and structural inheritance in the evolution of the Balaton Highland and the Veszprém Plateau during the Cretaceous Eoalpine compression. Palaeozoic and Triassic sediments of the study area are subdivided into tectonostratigraphic groups based on their rheological properties. A new simplified geological map of the Balaton Highland and Veszprém Plateau area was constructed. We briefly analyse the major Cretaceous compressional structures (e.g., the Litér thrust) based on our geological map and previous studies/literature review. The most significant lateral changes in competency occur within the Middle Anisian and Carnian sequences. The Middle Anisian and Lower Carnian geometries of the basin and the approximate palinspastic position of the basin and platform facies zones are also reconstructed.

Based on our interpretation, the ramp of the southwestern part of the Litér thrust was localised by the Carnian platform–basin transition. We argue that the lateral ramp between the two segments of the Litér thrust was localized by the zone of Middle Triassic platform–basin transition. In contrast, along the northeastern segment of the Liter thrust, Triassic facies boundaries were crosscut by the straight thrust fault without any significant change in its orientation.

Our model is in accordance with several analogue models, and natural examples worldwide: the related studies emphasize the fundamental role of pre-existing basin geometry in the development of the subsequent folding and thrusting. This study shows that the Balaton Highland is no exception.