Sedimentary architecture of Late Cretaceous to Early Eocene flysch sequences in the Swiss Alps

The Campanian/Maastrichian to Lutetian Alpine flysch sequences of the Schlieren- and Gurnigel nappes record deposition in an ocean-continent subduction setting related to Alpine orogenesis. Despite extensive studies of these flysch deposits, the existence of a source-to-sink relationship between the two units remains debated. Here, we logged 50-70 m-thick successions of the Gurnigel and Schlieren deposits at two sites, respectively, at a scale of 1:20. The ages of the analysed sediments range from the Thanetian to the Lutetian. We measured the paleoflow directions using sole marks and cross-bedding, and conducted drone surveys to document the large-scale depositional architecture. Our aim was to reconstruct a potential proximal-to-distal relationship between the two sequences.In the Schlieren nappe, the analysed sediments are dominated by coarse-grained (grain size up to 2 mm) sandstone beds