[1] Indiana Univ Penn, Dept Geosci, Indiana, PA 15701 USA
[2] Univ Kiel, Dept Organ Geochem, Inst Geosci, D-24118 Kiel, Germany
[3] Univ Hamburg, Ctr Nat Hist, D-20146 Hamburg, Germany
[4] Univ Hamburg, Inst Geol, D-20146 Hamburg, Germany
[5] Sodertorn Univ, Sch Nat Sci Technol & Environm Studies, S-14189 Huddinge, Sweden