title: Atomic force microscopy of Precambrian microscopic fossils.
abstract: Atomic force microscopy (AFM) is a technique used routinely in material science to image substances at a submicron (including nm) scale. We apply this technique to analysis of the fine structure of organic-walled Precambrian fossils, microscopic sphaeromorph acritarchs (cysts of planktonic unicellular protists) permineralized in approximately 650-million-year-old cherts of the Chichkan Formation of southern Kazakhstan. AFM images, backed by laser-Raman spectroscopic analysis of individual specimens, demonstrate that the walls of these petrified fossils are composed of stacked arrays of approximately 200-nm-sized angular platelets of polycyclic aromatic kerogen. Together, AFM and laser-Raman spectroscopy provide means by which to elucidate the submicron-scale structure of individual microscopic fossils, investigate the geochemical maturation of ancient organic matter, and, potentially, distinguish true fossils from pseudofossils and probe the mechanisms of fossil preservation by silica permineralization.
authors.affiliation: Institut für Kristallographie und Angewandte Mineralogie, Center for NanoScience, Ludwig-Maximilians-Universität München, Theresienstrasse 41, D-80333 Münich, Germany.
authors.forename: André
authors.initials: A
authors.lastname: Kempe
authors.forename: J William
authors.initials: JW
authors.lastname: Schopf
authors.forename: Wladyslaw
authors.initials: W
authors.lastname: Altermann
authors.forename: Anatoliy B
authors.initials: AB
authors.lastname: Kudryavtsev
authors.forename: Wolfgang M
authors.initials: WM
authors.lastname: Heckl
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005580:Fossils; D007623:Kazakhstan; D018625:Microscopy, Atomic Force; D010933:Plankton / Q000737:chemistry / Q000648:ultrastructure; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis; D013997:Time Factors
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons