3D morphology of a glacially overdeepened trough controlled by underlying bedrock geology

Gegg, Lukas; Deplazes, Gaudenz; Keller, Lorenz; Madritsch, Herfried; Spillmann, Thomas; Anselmetti, Flavio S.; Buechi, Marius W. (2021). 3D morphology of a glacially overdeepened trough controlled by underlying bedrock geology. Geomorphology, 394, p. 107950. Elsevier Science 10.1016/j.geomorph.2021.107950

[img]
Preview
Text
Gegg_et_al._2021_3D_morphology.pdf - Published Version
Available under License Creative Commons: Attribution (CC-BY).

Download (9MB) | Preview

Subglacial overdeepenings are common elements of mountain forelands and have considerable implications for human infrastructure. Yet, the processes of overdeepening by subglacial erosion and especially the role of bedrock geology are poorly understood. We present a case study of the Gebenstorf-Stilli Trough in northern Switzerland, a foreland overdeepening with a regionally unique, complex underlying bedrock geology: in contrast to other Swiss foreland overdeepenings, it is incised not only into Cenozoic Molasse deposits, but also into the underlying Mesozoic bedrock. In order to constrain the trough morphology in 3D, it was targeted with scientific boreholes as well as with seismic measurements acquired through analysis of surface waves. Our results reveal an unexpectedly complex trough morphology that appears to be closely related to the bedrock geology. Two sub-basins are incised into calcareous marls and Molasse deposits, and are separated by a distinct ridge of Jurassic limestones, indicating strong lithological control on erosional efficiency. We infer generally relatively low glacial erosion efficiency sensu stricto (i.e. quarrying and abrasion) and suggest that the glacier’s basal drainage system may have been the main driver of subglacial erosion of the Gebenstorf-Stilli Trough.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Quaternary Geology

UniBE Contributor:

Gegg, Lukas; Anselmetti, Flavio and Büchi, Marius

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0169-555X

Publisher:

Elsevier Science

Language:

English

Submitter:

Lukas Gegg

Date Deposited:

05 Oct 2021 18:22

Last Modified:

10 Oct 2021 03:10

Publisher DOI:

10.1016/j.geomorph.2021.107950

BORIS DOI:

10.48350/159709

URI:

https://boris.unibe.ch/id/eprint/159709

Actions (login required)

Edit item Edit item
Provide Feedback