Foreland basin evolution around the western Alpine Arc

Abstract

The arcuate form of the external western Alps was generated during Tertiary NW-directed collision between the Apulian indentor and the southward-subducting European passive margin. The evolution of peripheral syn-collisional depocentres around this arcuate orogen (in France and Switzerland) is reconstructed using a compilation of stratigraphic and tectonic data. This reveals fundamental changes in the flexural behaviour of the European lithosphere during collision. During early collision (Eocene), an increasingly arcuate, peripheral flexural basin migrated rapidly NW across the European plate. During peak collision (early Oligocene), frontal flexure, recorded in the North Alpine Foreland Basin (NAFB), steepened markedly, while lateral flexure of the European plate, affecting SE France, effectively ceased. Here, Oligocene sedimentation was confined to small thrust-sheet-top basins. Two rift systems initiating in the late Eocene, the West European rift system and the West Mediterranean oceanic basin (that created the Gulf of Lion passive margin), are superimposed in space and time on the outer margins of the alpine flexural depocentres. During waning collision (Mio-Pliocene) the NAFB became overfilled, then uplifted and abandoned while, in SE France, a local depocentre (Digne-Valensole) developed between uplifting blocks and continued to accumulate sediments until the late Pliocene.

Maximising data and precision from detrital zircon U-Pb analysis by LA-ICPMS: The use of core-rim ages and the single-analysis concordia age

“…Samples were collected from Oligo-Miocene clastic units of the Alpine pro-foreland basin (Ford and Lickorish, 2004). The sub-300 μm non-magnetic heavy mineral fraction was extracted from rock samples via standard crushing, sieving, and magnetic and density separation techniques.…”

Evidence for Cenozoic tectonic deformation in SE Ireland and near offshore

“…He showed that Alpine stresses were only transmitted into the foreland when they could not be accommodated within the orogen or flexural foreland basin. Ford and Lickorish [2004] provided evidence for continued flexural subsidence from Oligocene to late Miocene in the North Alpine Foreland basin. Subsequent alpine deformation and uplift is seen in the Paris Basin, the Rhine Graben, the Lulworth folds of southern Britain and Late Tertiary inversion in the North Sea.…”

The last erosional stage of the Molasse Basin and the Alps

“…While tensional subsidence of the northern parts of the upper Rhine Graben continued without interruptions to the present, its southern parts were uplifted by about 1,500 m during mid-Burdigalian time (18 Ma) in conjunction with the development of the Vosges-Black Forest Arch, involving lithosphere-scale folding (Ziegler et al 2002;Dèzes et al 2004;Ziegler and Dèzes 2007). Ford and Lickorish (2004) and Bourgeois et al (2007) proposed that this topographic high represented the Fig. 4 a Chronology of (i) sediment accumulation and erosion in the Molasse Basin, (ii) drainage direction in the foreland, and (iii) folding of the Jura fold-and-thrust belt.…”