The Swiss Alps and their peripheral foreland basin: Stratigraphic response to deep crustal processes

Abstract

This paper gives a synoptic view of the Cenozoic evolution of the Swiss Alps and their northern foreland basin. In this orogen, deep crustal processes (subduction, nappe stacking, Underplating, and exhumation) are intimately linked with surface processes (surface uplift, erosion, basin formation, and basin-axis migration). Within the foreland basin the spatial pattern of subsidence and alluvial fan construction suggests that an increase in flexure of the foreland plate and the creation of relief in the orogen migrated from east to west in the course of collision. In the orogen itself, crustal thickening involved lower crust of the Adriatic margin in the east and the European margin in the west. Exhumation of upper crustal units occurred earlier in the east as compared with the west. An Adriatic mantle wedge (the Ivrea body) and its associated wedge of lower crustal material are identified as an extra lithospheric load which contributed to downward flexure of the European plate. As a result of enhanced subsidence of the foreland plate, relief was generated presumably in order to adjust to critical taper geometry. It appears, therefore, that the westward motion of the Adriatic wedge ultimately caused the contemporaneous westward propagation of the location of enhanced rates of alluvial fan construction. Coeval strike-slip and N-S convergence juxtaposed the Adriatic wedge sequentially to different European upper crustal units which resulted in different styles of crustal structure and evolution along strike within the orogen. Copyright 2002 by the American Geophysical Union.