T108 Geologic Maps, Digital Geologic Maps, and Derivatives from Geologic and Geophysical Maps (Posters)

Monday, 1 November 2010
8:00 AM - 6:00 PM
Hall D

3D MODELLING OF UPPER CRETACEOUS STRATA BELOW A NEOGENE PULL APART BASIN (VIENNA BASIN, AUSTRIA)

Paper number: T108-12
Program: Technical Sessions
Time: 8:00 AM – 6:00 PM

Authors

Abstract

In the course of hydrocarbon exploration in the Vienna basin over the last 80 years numerous wells drilled the Alpine nappes below Neogene sediments. The nappesBotti formed during early stages of the Cretaceous collision of the Austroalpine tectonic unit and the European foreland. Upper Cretaceous sediments (Gosau Group) were deposited after the northwards oriented Eoalpine collision (95 Ma). The Gosau Formation was then partly eroded. Sediments to the south are proximal shallow marine deposits and within 100 km to the N form deep marine fan systems. This paper deals with the 3 dimensional distribution of the Gosau Formation that underlies Neogene pull-apart sediments. 90 wells reach Upper Cretaceous sediments at depths between 400 m and 5500 m TVD. Gosau sediments cover nappes comprising mostly Triassic and to lesser extent Jurassic Rocks.

We integrate well data into ArcGIS 9.2 to refine the structure of tectonic units below Neogene sediments. We further use sections to construct surfaces in GoCAD 2.5.2. The use of the same coordinate system in ArcGIS 9.2 and GoCAD provides interchangeable surfaces that can be constructed in three dimensions and then exported into a GIS database. Three dimensional representation of Austroalpine strata illustrates the geometry of the main thrust at he base of Austroalpine Units is a southwards dipping surface. Its steepness increases towards east by at least 20 degrees from 40-50 degree in the west to 60-70 degrees in the northeast. Once the angle gets steeper, nappes from the south thrust further northwards and simultaneously overthrust folded Gosau Sediments.