1. Lamont‐Doherty Earth Observatory Columbia University Palisades NY USA
2. Now at the Department of Geosciences The Pennsylvania State University State College PA USA
3. Department of Earth Sciences Syracuse University Syracuse NY USA
4. Department of Geosciences The Pennsylvania State University State College PA USA
5. School of Geosciences The University of the Witwatersrand Johannesburg South Africa
6. Geological Survey Department of Malawi Zomba Malawi
7. Geological Survey of Tanzania Dodoma Tanzania
8. Department of Geology University of Dar es Salaam Dar es Salaam Tanzania