[1
]Department of Arctic Geology; University Centre in Svalbard; N-9170 Longyearbyen Norway
[2
]Department of Earth Science; University of Bergen; N-5007 Bergen Norway
[3
]Geological Survey of Canada; Natural Resources Canada; K1A 0E8 Ottawa Ontario Canada
[4
]Leibniz Institute for Applied Geophysics; Section S3 D-30655 Hannover Germany
[5
]Nordic Laboratory for Luminescence Dating; Aarhus University; DK-4000 Roskilde Denmark
[6
]Centre for Nuclear Technologies, Denmark; Technical University; DK-4000 Roskilde Denmark