--> Abstract: Faulting and Related Sedimentation in the Austrian Molasse Basin During Oligocene and Lower Miocene, by R. Derksen; W. Tschelaut, and L. Wagner; #90942 (1997).

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Abstract: Faulting and related sedimentation in the Austrian Molasse basin during Oligocene and Lower Miocene

DERKSEN RICHARD; WERNER TSCHELAUT; LUDWIG WAGNER

Normal antithetic and synthetic faults displace the Mesozoic and Lower Tertiary in the Austrian Molasse Basin which belongs to the Alpine-Carpathian foredeep. The NW and NE trending fault systems developed during the Paleozoic and were reactivated later (Lower Jurassic, Lower Cretaceous, Lower Tertiary). During the latest Eocene and Early Oligocene, the central Paratethys subsided rapidly to deep water conditions. This was accompanied by the development of a dense network of predominantly W-E trending synthetic and antithetic tensional faults. This phase can be related to the flexural downbending of the foreland crust under the weight of the advancing Alpine nappe systems. In the late Tertiary and Quaternary the older faults were reactivated by transpressional foreland deformation resulting in sinistral and dextral strike slip faults. This phase is related to the collision of the Alpine orogenic system with the southern margin of the North European craton.

The influence of faulting on sedimentary processes is evident on seismic. Erosion surfaces cut into the preexisting basin fill preferentially above existing faults. Zones of weakness in the vicinity of faults guide deep erosion (bottom currents eroded deep into older sediments in front of the north-ward moving alpine nappe system). In the Oligocene and Lower Miocene these depressions were filled with slide material, turbidites and sediments reworked by bottom currents. Examples of the relationship between faulting and subsequent erosion and deposition in this Oligocene-Miocene slope and basin plain will be presented.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria