TAPHONOMY EXPERIMENTS AIMED AT CLARIFYING THE PROCESS OF PYRITIZATION IN PLANTS

Although pyritization of tissues is rare in the fossil record, it is one of the most valuable in terms of contributing to our knowledge of past life and environments. Exceptional preservation of pyritized tissues occurs in select Lagerstatten, fossilizing tissues and internal structures with incredible fidelity, sometimes on a cellular level. In order for pyritization of labile tissues to occur, specific conditions must be met, including: a source of carbon (decaying tissues), an anoxic environment, microbial reduction of sulfate, abundant available iron, porous sediments allowing diffusion and a steep chemical gradient. As of yet, pyrite replacement of leafy plant tissues has not been accomplished in fossilization experiments. Here we present preliminary results from an experiment aiming to recreate the natural conditions necessary for pyritization, modeled after the Eocene London Clay Lagerstatte. Triplicate experiments were run in which plant stems and leaves were buried in iron enriched estuarine sediments and seawater. Plant samples were harvested periodically, dehydrated and analyzed using microscopy (dissection microscope and SEM analysis) for rates of tissues decay and evidence of early pyritization. Controls of unburied stems and leaves were harvested on the same timeline as the experimental samples for decay comparisons. The results of this experiment will contribute important information to our understanding of the specific conditions required for the preservation of tissues through pyritization.