ATOMIC FORCE MICROSCOPY AS A TOOL FOR UNDERSTANDING DIATOM PRESERVATION

Diatoms are widely used in paleoclimatology, paleoceanography, and paleoecology. Historically, changes to diatom abundances and assemblages have been used to reconstruct past environments. More recently, diatom morphometric data have been incorporated into paleontological data sets. These approaches are valuable, however they do not address diatom taphonomy, which is significant in that it is tied to silicon cycling. Here I present preliminary results of a taphonomic study utilizing atomic force microscopy to analyze diatom changes to surface textures of artificially dissolved diatom valves. Atomic force microscopy creates data in three dimensions, making it an idea candidate to assess changes to surface texture and rates of dissolution of different valve components. Diatom valves recovered from a sediment trap deployed in the Ross Sea were subjected to artificial dissolution under laboratory conditions. Atomic force microscopy was used to assess changes in surface texture at regular stages during the dissolution process. Comparisons were made between centric and pennate diatoms, as well as valve face and more densely silicified margin and raphe silica. No differences were found between centric and pennate diatoms, however textural differences were found between valve parts. Silicification is, therefore, a more significant factor in controlling diatom taphonomy than phylogeny.