A paleomagnetic solution for the age controversy in the Upper Molasse of the Northern Alpine Foreland Basin

Abstract

– During the last two decades, research on the Western Paratethys and especially on the Northern Alpine Foreland Basin (Molasse) concentrated on improving the basin wide correlation because substantial uncertainties have led to considerable controversies, especially with regard to the dynamics of the basin’s depositional history. These uncertainties resulted in at least two widely different stratigraphic frameworks for the Bavarian and Swiss Molasse which results in ages that are about 1 Myr apart. This difference is mainly related to the assumption that a major hiatus is present in southern Germany, similar to the Styrian unconformity in Austria. The different opinions have led to different correlations of the Upper Molasse to either the Ottnangian or the Karpatian. The definitions, of these regional stages, are very strongly interconnected to each other, which will result in a review of the exact age of the Ottnangian – Karpatian boundary. To resolve this risen controversy a joint effort was undertaken. With new biostratigraphic, paleomagnetic and radiometric data from several key sections in Switzerland and from boreholes taken throughout Bavaria (Southern Germany) combined with data from the last decades resulted in the conclusion that the Ottnangian-Karpatian boundary has an age of 16.3 Ma (+/- 0.1 Myr). As a result the Karpatian becomes significant shorter in time than assumed before.