ICDP Project DOVE (Drilling Overdeepened Alpine Valleys): Seismic surveys across the sites

The panalpine project "DOVE" (Drilling Overdeepened Alpine Valleys), co-funded by the International Continental Scientific Drilling Program (ICDP), is drilling a series of overdeepened glacial troughs around the Alps that were formed by subglacial erosion during past glaciations. The sedimentary fill of these troughs, consisting of multiple stacked and nested glacial sequences, provides the best archives of when and where glaciers reached the Alpine forelands. The combined data from all DOVE sites comprising synchronous or asynchronous ice advances and ice extents in the different regions, will eventually provide a critical database to evaluate the various patterns in glacial-interglacial paleoclimates and landscape evolution back to the Mid-Pleistocene. In this context, we accomplished several seismic surveys at the Tannwald Basin and Basadingen Valley as well as the Lienz Basin. Deploying small-scale vibratory sources in vertical and horizontal orientations, we examined both P- and S-wave reflection imaging. We were able to image (1) the bedrock topography and (2) the interior of overdeepened valleys in high resolution in all investigated sites. Especially, the sedimentary succession and thickness of the deposits vary in detail across the sites. Even the infills of valleys in the same catchment area differ significantly (e.g. Tannwald Basin and Basadingen Valley in the Rhine Glacier arena). Nonetheless, foreland and intra-mountainous valleys show the same overall structure for each accumulation cycle (more or less from bottom to top: basal till, basin fines, fluvial deposits). As conclusion, a detailed seismic study of each overdeepened valley is mandatory for a comprehensive understanding of overdeepened structures.