1. Danish Lithosphere Center, Øster Voldgade 10, Copenhagen 1350, Denmark
2. School of Ocean and Earth Science and Technology, University of Hawaii, 2525 Correa Road, Honolulu, HI 96822, USA.
3. Department of Geology, University of Leicester, University Road, Leicester LE1 7RH, UK.
4. College of Oceanography, Oregon State University, Corvallis, OR 97331, USA.
5. Department of Earth Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA, UK.
6. Institute of Geophysics, University of Texas, Austin, TX 78759, USA.