Acknowledgements

We thank our Russian and German colleagues who helped in fieldwork in 2011 to obtain the samples. Nick Mewes is highly acknowledged for assistance in the laboratory. We also thank Cathy Jenks for English language proof reading. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 772852, ERC consolidator grant ”Glacial Legacy”) and the Initiative and Networking fund of the Helmholtz Association. LSE was supported by the German Research Foundation through grant EP98/2-1.