Postglacial evolution of Lake Constance: sedimentological and geochemical evidence from a deep-basin sediment core

Schaller, Sebastian; Böttcher, Michael E.; Buechi, Marius W.; Epp, Laura S.; Fabbri, Stefano C.; Gribenski, Natacha; Harms, Ulrich; Krastel, Sebastian; Liebezeit, Alina; Lindhorst, Katja; Marxen, Hanna; Raschke, Ulli; Schleheck, David; Schmiedinger, Iris; Schwalb, Antje; Vogel, Hendrik; Wessels, Martin; Anselmetti, Flavio (2022). Postglacial evolution of Lake Constance: sedimentological and geochemical evidence from a deep-basin sediment core. Swiss journal of geosciences, 115(1) Springer 10.1186/s00015-022-00412-1

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The modern, over 250-m-deep basin of Lake Constance represents the underfilled northern part of an over 400-m-deep, glacially overdeepened trough, which reaches well into the Alps at its southern end. The overdeep- ening was formed by repeated glacial advance-retreat cycles of the Rhine Glacier throughout the Middle to Late Pleistocene. A seismic survey of Lake Constance revealed a Quaternary sediment fill of more than 150 m thickness representing at least the last glacial cycle. The stratified sedimentary fill consists at the base of ice-contact deposits on top of the molasse bedrock, overlain by glaciolacustrine to lacustrine sediments. During the successful field test of a newly developed, mid-size coring system ("HIPERCORIG"), the longest core (HIBO19) ever taken in Lake Constance was retrieved with an overall length of 24 m. The sediments recovered consist of a nearly continuous succession of lacustrine silts and sands including more than 12 m of Late Glacial sediment at the base. 14 lithotypes were identified through petrophysical and geochemical analyses. In combination with a 14C- and OSL-based age-depth model, the core was divided into three main chronostratigraphic units. The basal age of ~ 13.7 ka BP dates the base of the succes- sion back to the Bølling-Allerød interstadial, with overlying strata representing a complete and thick Younger-Dryas to Holocene succession. The sediments offer a high-resolution insight into the evolution of paleo-Lake Constance from a cold, postglacial to a more productive and warmer Holocene lake. The Late Glacial succession is dominated by massive, m-thick sand beds reflecting episodic sedimentation pulses. They are most likely linked to a subaquatic channel system originating in the river Seefelder Aach, which is, despite the Holocene drape, still apparent in today’s lake bathymetry. The overlying Holocene succession reveals a prominent, several cm-thick, double-turbiditic event layer representing the most distal impact of the Flimser Bergsturz, the largest known rockslide of the Alps that occurred over 100 km upstream the river Rhine at ~ 9.5 ka BP. Furthermore, lithologic variations in the Holocene succession document the varying sediment loads of the river Rhine and the endogenic production representing a multitude of environmental changes.

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:

Schaller, Sebastian; Büchi, Marius; Fabbri, Stefano Claudio; Gribenski, Natacha Madeleine; Vogel, Hendrik and Anselmetti, Flavio

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

1661-8726

Publisher:

Springer

Language:

English

Submitter:

Flavio Anselmetti

Date Deposited:

10 Mar 2022 11:19

Last Modified:

10 Mar 2022 11:19

Publisher DOI:

10.1186/s00015-022-00412-1

BORIS DOI:

10.48350/166612

URI:

https://boris.unibe.ch/id/eprint/166612

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