1. Geological Survey of Estonia, Kadaka tee 82, 12618 Tallinn, Estonia;
2. Department of Earth Science & Astronomy, The University of Tokyo, Komaba, Meguro, 153-8902 Tokyo, Japan
3. Institute of Geology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia
4. Institute of Ecology and Earth Sciences, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
5. Department of Geology and Mineralogy, Kyoto University, 606-8502 Kyoto, Japan