Clay-varve data for the Younger Dryas and Preboreal in the Middle Swedish Ice Marginal Zone

Lars Brunnberg

A clay-varve chronology which covers the later part of the Younger Dryas stadial has been established in the easternmost part of the Middle Swedish Ice Marginal Zone. A slow ice retreat prevailed during 800–1000 years. An increased ice recession is recorded from 10,740 clay-varve years BP and onwards, shorttly after the last drainage of the Baltic Ice Lake, which took place c. 10,800 clay-varve years BP. The marine influence on sediments deposited in the Baltic basin after the drainage is recorded as a minor colour change. Much stronger signal is recorded at 10,430 clay-varve years BP when the Närke straits, in southern central Sweden, open up and a marine flora and fauna migrate into the Baltic. These changes are convincingly dated within the measured clay-varve sequences. They are recorded within the range of a few years. The deglaciation in this part of Sweden is correlated with the Ra moraines in Norway and the Salpausselkä ridges in Finland. The Swedish time scale, built on clay-varve chronology, has through the present investigation been extended to cover c. 13,000 years. The former floating time scales in the south of Sweden have been included.

Citation

Lars Brunnberg (2012) Clay-varve data for the Younger Dryas and Preboreal in the Middle Swedish Ice Marginal Zone. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/brunnberg-2012-varve-1

References

Brunnberg, L., 1995: Clay-varve chronology and deglaciation during the Younger Dryas and Preboreal in the easternmost part of the Middle Swedish Ice Marginal Zone. QUATERNARIA A:2. 94 pp.