1. Department of Environment, Earth and Ecosystems, Centre for Earth, Planetary, Space and Astronomical Research; Open University; Milton Keynes UK
2. Department of Earth Sciences; University of Oxford; Oxford UK
3. Organic Geochemistry Unit, The Cabot Institute, School of Chemistry; University of Bristol; Bristol UK
4. Now at School of Earth and Environment; University of Leeds; Leeds UK
5. School of Civil Engineering and Geoscience; University of Newcastle upon Tyne; Newcastle upon Tyne UK
6. Geological Institute; Russian Academy of Sciences; Moscow Russia