[1] Univ Durham, Environm Res Ctr, Durham DH1 3LE, England
[2] Geoforschungszentrum Potsdam, D-14473 Potsdam, Germany
[3] Fac Sci & Tech St Jerome, Lab Bot Hist & Polynol, F-13379 Marseille, France
[4] Alfred Wegener Inst Polar & Marine Res, D-14473 Potsdam, Germany
[5] Inst Mineral Petrol & Geochem, D-79104 Freiburg, Germany
[6] Alfred Wegener Inst Polar & Marine Res, D-27515 Bremerhaven, Germany
[7] Univ Dublin Trinity Coll, Dept Bot, Dublin 2, Ireland