Sedimentological and palynological constraints on the basal Triassic sequence in Central Switzerland

In Central Switzerland, Mesozoic sedimentation began after erosion and peneplainisation of the Hercynian relief and late Paleozoic continental deposition in SW-NE striking pull-apart basins. The first Triassic sedimentary sequence overlaying a weathered crystalline basement consists of a relatively thin (<10 m), lithologically highly variable unit with coarse-grained siliciclastic deposits at the base, grading into a mixed sandstone/shale-dolomite sequence followed by well-bedded dolomites with chert nodules.