1. Department of Geological Sciences, University of North Carolina, Chapel Hill, NC 27599-3315 USA
2. Universidade do Algarve, Faro, Portugal
3. University of Maine, Orono, ME, USA
4. Grand Valley State University, Allendale, MI, USA
5. Duke University, Durham, NC, USA
6. Monteiro, Instituto Geologico e Mineiro, Alfragide, Portugal