A Review of How Our Understanding on the Relationships between the Alps and the North Alpine Foreland Basin has Evolved

The North Alpine foreland basin or the Molasse basin that is situated on the northern side of the Alps has experienced a long history of research on its stratigraphic architecture, chronological framework, facies relationships, paleontological records and the provenance of its clastic material. Among these efforts, the most emphasis has been placed upon analyzing the Molasse basin as part of the Alpine orogenesis. Accordingly, the progress of Molasse research has been framed by advances in our knowledge, from a conceptual point of view, of how foreland basins evolve in response to crustal loading and erosional unloading in the adjacent mountain belt. Our understanding that has resulted from these conceptual investigations has changed over time, and so has our view on the development of the Alps/Molasse basin ensemble. This contribution recasts the history of research of the Molasse foreland basin, and it explains why particular mechanisms and the collection of related datasets have enjoyed more attention than others. It then ends with a call for a more careful exploration of how slab scale processes could have driven not only the development of the Alps, but also that of the Molasse basin, mainly because shifts in subduction and thus slab dynamics possibly explain the first order changes recorded in the evolution of this basin. These include (i) the transition from Flysch to Molasse sedimentation, which occurred in the Swiss part of the basin at 30 Ma and in the Austrian sector 10 Ma later, (ii) the ca. 18 Ma old reversal of the drainage direction in the basin axis, and (iii) the large-scale uplift and rebound of the entire basin since Pliocene times. The AlpArray initiative focuses on offering a bridge between surface dynamics, deep lithosphere structure and subduction mechanisms in the Alps. We postulate that the stratigraphic archive of the Molasse basin offers one of the cornerstones to link the processes on the surface with those in the mantle beneath the Alps.