2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 139-7
Presentation Time: 10:30 AM

PRECISE AND ACCURATE C-14 AGES FOR THE YOUNGER DRYAS FROM THE TYPE AREA IN SOUTHERN SCANDINAVIA


MANGERUD, Jan1, BIRKS, Hilary H.2 and LOHNE, Øystein S.1, (1)Department of Earth Science and Bjerknes Centre for Climate Research, University of Bergen, Allegt. 41, Bergen, 5007, Norway, (2)Department of Biology and Bjerknes Centre for Climate Research, University of Bergen, Bergen, 5020, Norway

Southern Scandinavia is the type area for the Younger Dryas as well as for the Bølling, Older Dryas and Allerød periods (Mangerud et al., 1974). We present Bayesian age-depth modelling of 118 AMS 14C dates from Kråkenes Lake, SW Norway, which were calibrated using INTCAL13. They provide high precision ages of 12 737 ± 31 and 11 535 ± 58 cal yrs BP (=B1950) for the onset and end of the Younger Dryas respectively (Lohne et al., 2013, 2014). The larger error on the younger boundary is due to the 14C plateau.

We also obtained ages of 12 064 ± 48 and 10 210 ± 35 cal yrs BP for the mid-YD Vedde and the early-Holocene Saksunarvatn ashes respectively. The ages of these four dated levels coincide with correlative levels in Greenland ice cores (GICC05) within the dating uncertainties, but all are consistently younger at Kråkenes. The ages of the tephra chronostratigraphic markers suggest a mean offset of ~70 years to older ages in the GICC05 compared to the INTCAL13 time scale. Responses to small climate changes ~30 years before the YD boundaries at Kråkenes are suggested to correspond to the defined Greenland Stadial-1 (GS-1) boundaries. This suggested difference in timing (30 years) and the time-scale offset (70 years) mean that the GS-1 boundaries appear to be ~100 years older than the YD boundaries.

Lohne, Ø.S., Mangerud, J., Birks, H.H., 2013. Precise 14C ages of the Vedde and Saksunarvatn ashes and the Younger Dryas boundaries from western Norway and their comparison with the Greenland Ice Core (GICC05) chronology. Journal of Quaternary Science 28, 490-500.

Lohne, Ø.S., Mangerud, J., Birks, H.H., 2014. IntCal13 calibrated ages of the Vedde and Saksunarvatn ashes and the Younger Dryas boundaries from Kråkenes, western Norway. Journal of Quaternary Science 29, 506-507.

Mangerud, J., Andersen, S.T., Berglund, B.E., Donner, J.J., 1974. Quaternary stratigraphy of Norden, a proposal for terminology and classification. Boreas 3, 109-128.

Session No. 139

T32. Younger Dryas and Other Dansgaard-Oeschger Events in the Northern and Southern Hemisphere (Posters)
Monday, 20 October 2014: 9:00 AM-6:30 PM
Exhibition Hall C (Vancouver Convention Centre-West)
Geological Society of America Abstracts with Programs. Vol. 46, No. 6, p.349
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