1. Geological Survey of Norway, Leiv Eirikssons vei 39, NO-7040 Trondheim, Norway
2. Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen, Denmark
3. Institute of Geology and Mineralogy University of Cologne, Zülpicher Str. 49a, DE-50674 Köln, Germany