1. J. G. Ryan, Department of Geology, University of South Florida, Tampa, FL 33620, USA, and Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA.
2. J. Morris and F. Tera, Department of Terrestrial Magnetism, Carnegie Institution Washington, Washington, DC 20015, USA.
3. W. P. Leeman, Department of Geology and Geophysics, Rice University, Houston, TX, USA.
4. A. Tsvetkov, Institute of Mining and Mineral Resources, Russian Academy of Sciences, Moscow, Russia.