Original paper

Herkunft und Transport der Sedimente im bayerischen Flyschtrog

Hesse, R.

Abstract

Outcrops of the "Flysch-Gault", Lower Cretaceous, Bavarian Alps, have been correlated bed-by-bed over an area of 120 km (W-E) x 10 km (N-S). The criteria for the correlation are: a) thickness of the graywacke beds and of the shales between them, b) mineral composition at the base of the beds. The correlated series has a thickness of about 200 m. The graywacke beds are 1 m thick on an average. Grain size in most beds continuously decreases from W to E; feldspar content of feldspar-rich beds shows the same tendency. Current directions from W to E have been prooved by flute casts, groove casts etc. The three facts: 1) bed-by-bed correlation over long distances, 2) direction of decrease of grain size and feldspar content, 3) direction of sediment structures lead to the conclusion, that sediments have been brought from W into the flysch trough and were transported parallel to its axis. Directional structures of Middle Cretaceous flysch sediments indicate transport from the opposite side (from W to E). The currents of Upper Cretaceous time again came from W (s. a. v. RAD, 1964). These observations are interpreted by the following hypothesis: During Cretaceous time the deep-sea flysch trough was occupied by a horizontally circulating current. It seems that in Lower and Upper Cretaceous times our observations deal with one (? southern) part (direction: W to E) and in Middle Cretaceous time with the other (? northern) part (direction: E to W) of this? counter-clockwise circulating current.