PMC

(a) Cumulative thicknesses of Molasse units across a S–N section and locations relative to the orogen front where sediment accumulation has occurred. Inset Figure next to the legend illustrates the orientation of the section, which is identical as . (b) Chronologic (Wheeler) diagram for Molasse units across the basin. The figure has been modified from Sinclair et al. and expanded for post 15–12-Ma-old units, which have been eroded and recycled after 5–6 Ma (ref , ). NLB=Northern Limit of Basin. For orientation of section see figure next to the legend. (c) Chronologic (Wheeler) diagram for Molasse units for a section that parallels the proximal basin border (see inset figure next to the legend for orientation of section). The numbers 1 (ref. ), 2 (ref. ), 3 (ref. ), 4 (ref. ) and 5 (ref. ) correspond to the sources of the magnetostratigraphic data. Sections labelled with 6 (ref. ) and 7 (ref. ) have been analysed for the time and the amplitude of basin erosion on the basis of fission track data established for detrital apatites encountered in drillings. Isopachs for non-decompacted Molasse sediments are based on thicknesses of magnetostratigraphic sections. The inset Figure next to the legend illustrates the Alps, the Molasse and Po Basins together with the orientation of the sections.

(a) Evolution of palaeoclimate based on δ¹⁸O records. (b) Paleoclimate proxy data collected in the Molasse Basin. Leg. = Leguminosae, Pop. = Populoid, Eng. = Engelhardia, Tax. = Taxodiacea.

(A) Map of a part of Western Europe showing the location of Switzerland. (B) Enlargement of the Aquitanian paleogeographical context of the Swiss Molasse Basin, with detailed location of Wischberg locality (star symbol).

(a) Sediment discharge from the Central Alps to the Molasse basin, which has been measured based on preserved volumes of rocks derived through erosion of the Alps (figure adapted from Schlunegger and Kissling). (b) Stratigraphic architecture of the Molasse deposits within a temporal framework. Note that the change from basin underfill to overfill c. 30 Ma ago (1^st signal) coincides with the time when the topography started to build up in response to slab breakoff (). The arrival of the 2^nd signal was marked by rapid fan progradation (based on Schlunegger and Kissling). (c) Restored palaeogeographic situation of the Molasse basin at c. 25 Ma. The dashed lines indicate the cumulative thicknesses of material that accumulated between 30–25 Ma. The map has been drawn on the basis of Pfiffner et al. using Illustrator 15.1.0 licenced to Uni Bern. (d) 3D reconstruction of the architecture of the Molasse basin at c. 25 Ma based on Schlunegger et al.. The floodplain represents an alternation of sandstones and mudstones; wandering streams accumulated a succession of alternated conglomerate and mudstone beds; braided streams are recorded by amalgamated conglomerate beds. Local fans, or ‘bajada’ fans, are recognized by alternated debris-flow conglomerates and mudstones (see also ). The dashed lines represent isochrones. The sections of (black vertical line) are slightly offset of the fan apex.