High‐resolution reflection seismics reveal the structure and the evolution of the Quaternary glacial Tannwald Basin

Abstract

Over‐deepened basins exist throughout the Alpine realm. Improving our knowledge on these basins is of high social relevance, since these areas are often well‐populated and they possess, for instance, unusual hydrological settings. Nonetheless, geophysical and sedimentological investigations of over‐deepened basins are rare. We analyse the sedimentary succession of such a basin, the Tannwald Basin, through geological interpretation of seismic reflection profiles. The basin is located approximately 60 km north of the European Alps. It was incised into Tertiary molasse sediments by the Rhine Glacier and later filled by glacial, fluvial, and lacustrine deposits of 250 m thickness. The Leibniz Institute for Applied Geophysics acquired a grid of five high‐resolution seismic reflection lines that imaged till the deepest parts of the Tannwald Basin. The seismic profiles, processed to a pre‐stack depth migration level, allow a detailed geological interpretation that is calibrated with the help of a nearby borehole. We determine the structure and the seismic facies of the sediment succession in the basin and presume the following hypothesis of the evolution of the basin: sub‐glacial erosion comprises the excavation of the over‐deepened basin as well as detachment of large fragments of molasse material. These molasse slabs were deposited within the basin in a layer of basal till that graded upwards in water‐lain till and fine‐grained deposits. During the last two glaciations, the basinal structure became buried by till sequences and glacio‐fluvial sediments.

Seismic P Wave Velocity Model From 3‐D Surface and Borehole Seismic Data at the Alpine Fault DFDP‐2 Drill Site (Whataroa, New Zealand)

“…These undulations are smooth but highly variable in 3‐D and thus might be caused by former glacial erosion. Similar features are also observed by other seismic studies in glacial valleys (e.g., Ahmad et al, ; Büker et al, , ; Burschil et al, , ; Lukács et al, ; Ogunsuyi & Schmitt, ).…”

Seismic P Wave Velocity Model From 3‐D Surface and Borehole Seismic Data at the Alpine Fault DFDP‐2 Drill Site (Whataroa, New Zealand)

“…These undulations are smooth but highly variable in 3-D and thus might be caused by former glacial erosion. Similar features are also observed by other seismic studies in glacial valleys (e.g., Ahmad et al, 2009;Büker et al, 2000Büker et al, , 2010Burschil et al, 2018Burschil et al, , 2019Lukács et al, 2018;Ogunsuyi & Schmitt, 2010).…”

Shallow seismic reflection survey for imaging deep-seated coal layer - Case study from Muara Enim coal

“…Since around 1980, seismic reflection has been used not only for geotechnical and environmental purposes but also for underground coal exploration at which the depths of the target are typically less than 500 meters or shallow. Presently, the application of shallow seismic reflection survey includes mapping the quarternary deposits (Okkonen and Moisio, 2015;Maraio et al, 2018), buried rock valleys and shallow faults Burschil et al, 2018), hydrogeology studies (Al-Shuhail and Adetunji, 2016;Miller et al, 2016), mineral exploration (Hajnal et al, 2015;Malehmir et al, 2015), geotechnical investigation and hazard mitigation (Baradello and Accaino, 2016;Dehghannejad et al, 2017).…”