Lee E.Y.1 , Novotny J.2 , Decker K.1 , and Wagreich M.1
EU-Korea Conference on Science&Technology, Vienna, Austria, 22-25 July 2014.

Abstract

The Vienna Basin is a tectonically complex Miocene pull-apart basin situated at the Alpine-Carpathian transition. This study analyses the subsidence history of the basin by the backstripping technique to understand its tectonic evolution. Data were derived from 100 boreholes which were sorted into 10 groups based on their position. 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.

Backstripping is a technique for progressively removing the sedimentary load from a basin, in order to reveal the tectonic driving mechanisms of basin subsidence. The subsurface of the subsided depths is reconstructed by utilizing the Thin-Plate Spline Interpolation in MATLAB.

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 of the basin. In the northern part, the subsidence decreases markedly, whereas the central part is characterized by gradually decreasing subsidence pattern and prolonged tectonic subsidence.

There were two suggestions to explain the different subsidence patterns observed in the Vienna Basin. The first model [1] 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 Vienna 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.

The second suggestion [2] proposed a post-rift (thermal) subsidence for the central part of the Vienna Basin. 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. However, there is no major thermal anomaly arguing for lithospheric extension and the heat flow is low (45-60 mW/m2). Additionally, in such a small size basin (60 km by 200 km), the coexistence of two extension types seems highly speculative.

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. This is related to active sinistral tectonics indicated along the southeastern part of the Vienna Basin. This study promotes approaches that active tectonics might influence on the gradually decreasing subsidence pattern and the ongoing tectonic subsidence of the central part.

Keywords: Vienna Basin, Subsidence, Tectonics, Extension, 3D Modelling


[1] Lankreijer, A., Kovac, M., Cloetingh, S., Pitonak, P., Hloska, M., and Biermann, C., 1995.
Quantitative subsidence analysis and forward modelling of the Vienna and Danube basins: thin-skinned versus thick-skinned extension.
Tectonophysics 252, 433-451.

[2] Royden, L.H., 1985.
The Vienna basin: a thin-skinned pull apart basin.
In: K. Biddle and K. Christie-Blick (Editors), Strike-Slip Deformation, Basin Formation and Sedimentation. SEPM Spec. Publ., 37, 319-339.


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