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Abstract:
The basin sediments of Lake Constance encompass superior records of glacial to late glacial and Holocene environmental conditions but were hitherto not recovered from greater depths due to the lack of high-quality but inexpensive coring instruments. In a test and commissioning campaign in 2019, a new scientific coring device, called Hipercorig, was deployed and recovered from two parallel boreholes a 20 and a 24 m long drillcore and one two-m-long surface core (Harms et al. 2020, Schaller et al. 2022). The drill site is in 200 m deep waters close to the northwestern lake shoreline near the town of Hagnau and was selected based on new seismic surveys. They revealed an up to 150 m thick sediment fill of the overdeepened Lake Constance basin created by several advance and retreat cycles of the Rhine Glacier during the mid to late Quaternary. The deposits comprise proglacial sediments overlain by glaciolacustrine and finally lake strata. The latter make up the top 12 m of the core recovered while below sandy intercalations indicate downward increasing influence of dynamic sedimentation pulses that were deposited through subaquatic channel systems fed by declining glaciers and meltwater pulses from the north. The cores retrieved were sampled for microbiology and pore fluids at University of Constance (Germany). They were opened at Bern University (Switzerland) in fall 2019, sedimentologically described, instrumentally logged, and sampled for further studies including age dating. These data served to identify 14 lithotypes that were differentiated into three chronostratigraphic units based on a 14C- and OSL-based age model. The cores section base with the proglacial unit is about 13.7 ka BP old while the lacustrine strata cover Bølling-Alerød and Holocene ages. A prominent turbiditic event layer could be dated at 9.5 ka BP, coeval with the largest Holocene Alpine rock slide, the Flimser Bergsturz, that caused damming of the river Rhine and finally an outburst reaching as turbidite even northern Lake Constance. These initially gained data sets and the instruments utilized are described in the data description.
