Palaeogeography of alpine flysch
Abstract Palaoegeography of alpine basins during times of flysch sedimentation is reconstructed from an approach based upon global tectonic constraints, on palinspastic reconstruction from regional geology, and on the sedimentalogy of individual flysch sequences. The opening of the central Atlantic ocean, coincident with the formation of the Western Mediterranean Tethys, implied left-lateral movement between Africa and Europe during the break-up of Pangea. Whereas “N-S” trending margins of this part of oceanic Tethys would have been predominantly passive, the “E-W” trending northern margin would have been a major transform zone. The combination of these broad constraints with detailed palinspastic reconstruction of the area considered, provides an approximate, Early Cretaceous palaeogeography of that part of the Western Mediterranean Tethys which was to build the Western Alps. Flysch sediments had not yet appeared on the scene. The subsequent openings of the South Atlantic and the North Atlantic Oceans, together with their spreading rates, provide constraints on the movement of Africa (and therefore Adria, the southern and eastern margin of the oceanic basin concerned) with respect to Europe. These movements are tied in with the sedimentology of alpine flysch sequences to provide map views of the northern part of the Western Mediterranean Tethys during its closure (Late Cretaceous to Palaeogene). A number of apparently conflicting views and theories on flysch palaeogeography may be reconciled by this approach.