LIAG
 

Multi-component seismics in overdeepened Alpine basins

Fig. 1: Alpine region with locations of over-deepened valleys and basins (red), and drilling locations (numbered) suggested in the recent ICDP proposal DOVE (Anselmetti et al. 2014; unpubl.). Red number: Tannwald Basin; green number: Lienz Basin; pink line: limits of the Last Glacial Maximum; black line: maximum limit of Pleistocene glaciation.

In the Alps a systematic attempt to unravel the processes and controlling factors of overdeepening and subsequent sedimentation, the spatio-temporal extent of the different glaciations, and the spatial complexity of the sediments of overdeepened structures is still missing.  The ICDP proposal DOVE (Drilling Overdeepened Alpine Valleys; Anselmetti et al., 2014) wants to close this gap.

This project is part of the international initiative, and aims at an improved seismic characterization of overdeepened Quaternary valleys and basins in formerly glaciated, mountainous areas.  The term ‘overdeepened’ refers to the genesis of these valleys and basins, which are of glacial origin.

Overdeepened structures exist worldwide.  In the European Alps, overdeepening resulted in buried elongated valleys, mainly oriented in the direction of former ice flow, and glacially scoured basins in the ablation area of glaciers (Fig. 1).  After the retreat of the glaciers most overdeepened structures were quickly filled by glacial and glaciolacustrine deposits.  For the inner-Alpine valleys it is assumed – but not finally proven – that recurring glaciations removed major parts of the infill, whereas in the Alpine foreland usually significant portions of the older sediments remained in place.

Open questions we want to address in the Tannwald and Lienz Basins are:

  • provision of 3-D structural information with reflection seismics to determine basin depths, potential faults, and major reflections,
  • characterization of multi-phase glacial deposition and erosion, facies, and features resulting from mass movements,
  • application of P-wave seismics, shear-wave seismics, and multi-component seismics to provide a clue to anisotropy.

Project-relevant literature:

  • Buness, H., 2007. Improving the processing of vibroseis data for very shallow high-resolution measurements. Near Surface Geophysics, 5(3), 173-182.
  • Burschil, T., Beilecke, T. & Krawczyk, C.M., 2015. Finite difference modelling to Evaluate Seismic P-Wave and Shear Wave Field Data.  Solid Earth, 6, 33-47; doi: 10.5194/se-6-33-2015.
  • Ellwanger, D., Wielandt-Schuster, U., Franz, M. & Simon, Th., 2011. The Quaternary of the southwest German Alpine Foreland (Bodensee-Oberschwaben, Baden-Württemberg, Southwest Germany). E & G Quaternary Science Journal, 60 (2-3), 306-328; doi: 10.3285/eg.60.2-3.07.
  • Gabriel, G., Ellwanger, D., Hoselmann, C., Weidenfeller, M., Wielandt-Schuster, U. & The Heidelberg Basin Project Team,2013. The Heidelberg Basin, Upper Rhine Graben (Germany): a unique archive of Quaternary sediments in Central Europe. Quaternary International, 292, 43-58.
  • Krawczyk, C.M., Polom, U. & Beilecke, T., 2013. Shear-wave reflection seismics as valuable tool for near-surface urban applications. The Leading Edge, 32 (3), 256-263; doi: 10.1190/tle32030256.1.
  • Polom, U., Bagge, M., Wadas, S., Winsemann, J., Brandes, C., Binot, F. & Krawczyk, C.M., 2013. Surveying near-surface depocentres by means of shear wave seismics. First Break, 31 (8), 63-75.