10Be dating of Younger Dryas Salpausselkä I formation in Finland

Boreas - Tập 29 Số 4 - Trang 287-293 - 2000
Silvio Tschudi1, Susan Ivy‐Ochs2, Christian Schlüchter3, Peter W. Kubik4, H. Rainio5
1Institute for Geology, University of Bern, c/o Institute of Particle Physics, ETH Zürich, 8093 Zürich, Switzerland
2Institute for Geology, University of Bern, c/o Institute of Particle Physics, ETH Zürich, Switzerland
3Institute for Geology, University of Bern, 3012 Bern, Switzerland
4Paul Scherrer Institut, c/o Institute of Particle Physics, ETH Zürich, 8093 Zürich, Switzerland
5Geological Survey of Finland, 02151 Espoo, Finland,

Tóm tắt

Boulders of the Younger Dryas Salpausselkä I (Ss I) formation west of Lahti, southern Finland, were sampled for surface exposure dating. The 10Be concentrations, determined by accelerator mass spectrometry, yield minimum exposure ages of 11 930 ± 950, 11 220 ± 890, 11 050 ± 910 and 11 540 ± 990 years, using recently published production rates scaled for latitude and elevation. This includes a correction to the production rate resulting from postglacial uplift of the Fennoscandian lithosphere (i.e. changing elevation) during the time of exposure. The error‐weighted mean exposure age of 11 420 ± 470 years of the analysed boulders agrees with previous varve dates of Ss I, which range from 11 680 to 11 430 calendar years BP. However, erosion has to be taken into account as a process affecting rock surfaces and therefore influencing exposure ages. Available information suggests an erosion rate of 5 mm/kyr, which increases the error‐weighted mean exposure age to a value of 11 610 ± 470 years. Within the errors, the formation of Ss I in the Vesala area west of Lahti falls into the Younger Dryas time bracket, as defined by the GRIP and GISP 2 ice core (Greenland).

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Boreas

Tập 29 Số 4

287-293

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