Magnetostratigraphy and small mammals of the Late Oligocene Banovići basin in NE Bosnia and Herzegovina

Abstract

A combined magnetostratigraphic and small mammal investigation was carried out to acquire better age control on the sedimentary infill of the Banovići basin in Bosnia and Herzegovina. Although the Dinarides occupy a crucial paleogeographic position bridging Central Europe and Anatolia no detailed records of its small mammal fauna have been published until now. A rich small-mammal assemblage with over 500 molars was excavated from a section exposing marls and clays just underlying the basins main coal layer. The fauna of this Turija small-mammal locality compares best with the uppermost Oligocene to lowermost Miocene localities from the European MP30/MN1 mammal zones and with Anatolian zone B from central Turkey. A 160 m thick series of lacustrine sediments, overlying the main coal layer in the nearby Grivice section, was sampled for paleomagnetic purposes. The magnetostratigraphic pattern of the Grivice section comprises a long reversed interval, a subsequent short normal interval, and another reversed interval. The most logical correlation of this pattern to the Late Oligocene part of the Geomagnetic Polarity Time Scale (GPTS) is to chrons C6Cr, C6Cn.3n and C6Cn.2r (24 to 23.2 Ma). This correlation implies a sedimentation rate of ~20 cm/kyr for the Banovići basin, and an age of approximately 24 Ma for the Turija mammal site. The proposed correlation fits well with other magnetostratigraphically calibrated mammal records in western and central Europe as well as Anatolia, and with the recalibrated ages of 24.95±0.05 Ma and 24.72±0.04 Ma for two basalt flows bracketing the Enspel MP28 site in Southern Germany. Our results indicate that a limited exchange of fauna from central Asia to western Europe existed in Late Oligocene and Miocene times.