1. Department of Geology, University of Johannesburg, Auckland Park 2006, South Africa
2. Beijing SHRIMP Center, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Road, Beijing 100037, China
3. Institut für Geowissenschaften, Universität Mainz, 55099 Mainz, Germany
4. School of Geosciences, University of the Witwatersrand, 2050 Wits, South Africa
5. Institute of Geology of the Karelian Research Centre, Russian Academy of Sciences, Petrozavodsk, Russia