High resolution Late Miocene sediment accommodation rates and subsidence history in the Austrian part of the Vienna Basin

Abstract

We present the first detailed intra-basin correlation of Upper Miocene deposits in the Austrian part of the Vienna Basin (VB) integrating the most important hydrocarbon fields. Herein, we use a high resolution dataset by separating the Pannonian (= Tortonian) stack into 20 lithostratigraphic units, which allow calculating regional differences in sedimentation rates over a time span of ∼1.6 Ma. During this time span we recognize an initial phase of high lateral variability in thicknesses, reflecting the influence of paleo-topography on deposition during the early Pannonian. The relief difference of about 300 m was rapidly filled by lake marls and delta lobes of the Paleo-Danube. Subsequently, lateral variability in sediment thicknesses declined strongly around 11.0 Ma. At that point the relief was largely sealed, and subsidence became the controlling factor. Our data document a shift of high subsidence rates from the southern VB to the northern VB into three steps, initiated by increased activity of the Steinberg Fault around 10.5–10.4 Ma. Sedimentation rates have been declining during the early Pannonian but reveal a strong pulse in subsidence during the middle Pannonian. The still high sedimentation rates during the late Pannonian indicate persisting extensional tectonics in the VB throughout the Late Miocene and question the prevailing tectonic model of a compressional regime for this time. The lack of uppermost Pannonian deposits in most wells documents a post-Pannonian erosion of about 400 m in large parts of the VB.