Integrated stratigraphy of the Sarmatian (Upper Middle Miocene) in the western Central Paratethys

Abstract

The Vienna Basin and the Styrian Basin have been cornerstones for the definition and description of the Central Euro-pean Sarmatian Stage. New inter-and intrabasin correlations of well-logs and surface outcrops reveal a rather uniform development of depositional systems in all considered basins, which excludes local autocyclic processes as the sole trigger. The lithostratigraphy of these basins is critically summarized and the Wolfsthal Member is introduced as a new lithostratigraphic unit. The more than 1000-m-thick Sarmatian basin-fill is recorded in geophysical logs by a characteristic succession of serrated funnel-to bell-shaped curves separated by shale-line intervals. The correlative floodings are well preserved in marginal settings and accessible in surface outcrops. Slight falls of the relative sea-level are also reflected in the littoral zone by erosive surfaces, caliche formation and progradation of fluvial facies. The stratigraphic position and duration of the Sarmatian suggests a relation to the 3 rd order cycle TB. 2.6. Internally, two 4 th order cycles are depicted. An exact correlation with Mediterranean standard stages and the "Haq-cycles" is difficult due to the endemic marine fauna that flourished in the nearly land-locked Paratethys Sea during the Sarmatian. This obstacle may be overcome by a first cautious calibration of the sedimentary sequence with astronomical target curves. Hence, the 400-Ka eccentricity component might have triggered the 4 th order cycles, with the maximum flooding surfaces coinciding with the maxima of that band. An overall trend from a pelitic-siliciclastic Lower Sarmatian 4th order cycle towards an oolitic Upper Sarmatian 4 th order cycle could be forced by the inflection of the 2.35-Ma component. The tentative calibration requires a new positioning of the Badenian/Sarmatian boundary close to 12.7 Ma, which would fit excellently to the glacio-eustatic isotope event MSI-3. The coincidence of the final retreat of the sea from the Molasse Basin with a major phase of progradation of alluvial fans into the Styrian and the Vienna Basins suggests a pulse of uplift in the eastern Alpine region at 12.1-12.3 Ma.