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

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