Post-EX5 Sat 15. September 2018 1 day
Mass transport deposits, geometry, depositional regime and biostratigraphy in a Late Jurassic carbonate-clastic radiolaritic basin fill (Salzburg Calcareous Alps)
Guide: Hans-Jürgen Gawlick, Hisashi Suzuki & Sigrid Missoni
This field trip will provide insights in the geometry of a Late Jurassic deep-water radiolaritic trench-like basin formed related to thrusting (Oxfordian). This phase (first cycle) of the basin evolution is characterized by a coarsening-upward trend. This cycle of deposition is characterized by redeposition of older clasts. In the Kimmeridgian (second cycle) the basin the basin becomes starved. In the Tithonian (third cycle) the sedimentation trend change to a fining-upward trend, indicating extension. This cycle shows in the first phase redeposition of older clasts and later the deposits were typically made of a mixture of older clasts and contemporaneously formed reef debus. In the latest stage, the redeposits exclusively consisted of shallow-water carbonates originated from a newly formed platform. In general, sedimentation is characterized by fine-grained siliceous and organic-rich sedimentation with intercalation of various mass transport deposits (slumps, debris flows, olistostromes and slide blocks). In the proximal basin part the thickness of the basin fill is nearly 800 m, whereas in the central part of the basin the thickness reaches 200 m and in the most distal part of the basin only few tens of meters were deposited. The triggering factors of mass transport movements are various, i.e. earth quakes, volcanism and can be studied in well preserved outcrops. In addition, the Jurassic geodynamic evolution of the Northern Calcareous Alps will be discussed.