1. Department of Geosciences; Princeton University; Princeton New Jersey USA
2. Department of Geology and Planetary Science; University of Pittsburgh; Pittsburgh Pennsylvania USA
3. Department of Geosciences; University of Tübingen; Tübingen Germany
4. Department of Geology; University of Cincinnati; Cincinnati Ohio USA
5. Department of Geological Sciences; University of North Carolina at Chapel Hill; Chapel Hill North Carolina USA
6. Now at U.S. Geological Survey; Anchorage Alaska USA