Lee E.Y.1 , Novotny J.2 , Decker K.1 , and Wagreich M.1
19th International Sedimentological Congress, 18-22 August 2014.

Abstract

This study analyzes a detailed quantification of subsidence in the central and the northern parts of the Vienna Basin by backstripping and 3D modelling technique to understand its tectonic evolution. Backstripping is a technique for progressively removing the sedimentary load from a basin, in order to reveal the tectonic driving mechanisms of basin. And, the 3D model is reconstructed by utilizing the Thin-Plate Spline Interpolation in MATLAB. The Vienna Basin is a tectonically complex Miocene pull-apart basin situated between the Alps, the Carpathians, and the Pannonian Basin System. About 100 boreholes were investigated in the basin, and sorted into 10 groups based on their position within the same block bordered by major faults. Compared to other publications on this topic, this study provides a more accurate analysis by the high density of considered boreholes, the geophysical evaluation of the porosity-depth relation, and the use of 3D modelling.

During the Early Miocene, subsidence was shallow and producing NE-SW trending depocenters during the development of a piggy-back basin. From the late Early Miocene onwards data show very high subsidence rates caused due to sinistral transtension, which initiates pull-apart basin system. Subsequently, the curves show decreasing overall subsidence, however subsidence decreases leading to distinct subsidence patterns in the northern and the central parts. In the northern part, the subsidence decreases markedly, whereas the central part is characterized by gradually decreasing pattern and prolonged tectonic subsidence.

There were two suggestions to explain the different subsidence patterns observed in the Vienna Basin. The first suggestion proposed a post-rift (thermal) subsidence for the central part. Thus, the Vienna Basin comprises a non-uniform extensional basin changing from thin-skinned extension in the northern part to whole lithospheric extension in the central part. It suggested also that the deep-rooted strike-slip faults reactivated the pre-existing fault planes which penetrated locally into the overlying thrust belt and created a new structural regime. However, there is no major thermal anomaly arguing for lithospheric extension and the heat flow is low. Additionally, in such a small size basin, the coexistence of two extension types seems highly speculative.

The second model presented that the Vienna Basin provides an excellent example of how thin-skinned extension can create a sedimentary basin. It explained that post-extensional (or thermal) subsidence within the basin is impossible, because the extension and the associated strike-slip faulting were restricted to shallow levels. It analyzed subsidence curves of the basin for two different cases; (1) for the northeastern part, where most of the subsidence and sedimentation is of Early Miocene age or older, and (2) for the south-central part, where most of the subsidence is of the Middle to Late Miocene age. The model, however, fails to explain why subsidence happened locally in different times, and the study analyzed uncorrected subsidence curves neglecting compaction of sediments.

Later studies of the Vienna Basin argue for polyphase thin-skinned extension and present that some extension and faulting have probably occurred until recently, or are still ongoing. In this study, 3D modeling allowed us to gain better insight into the data and helped to improve the theoretical models for the tectonic evolution of the Vienna Basin. It promotes approaches that active tectonics might influence on the subsidence patterns observed in the basin.


1Department of Geodynamics and Sedimentology, University of Vienna, Vienna, Austria
2Institute of Computer Graphics and Algorithms, Vienna University of Technology, Vienna, Austria