A NEW ANALYSIS OF RAMPED TEMPERATURE PYROLYSIS METHODS AS THEY APPLY TO ANTARCTIC SEDIMENT CHRONOLOGY, RADIOCARBON DATING, AND PALEOENVIRONMENTAL INTERPRETATION

This study attempts to analyze the feasibility of ramped temperature pyrolysis methods for use in radiocarbon dating of organic matter-rich Antarctic marine shelf sediments. An analysis of the hydrochloric acid-insoluble organic component of five samples from separate depths of the marine core allows for the ultimate assignment of ages to these sediments by radiocarbon dating methods. As part of the Larsen Ice Shelf system (LARISSA) project, this core is unique in that it spans the last 12,000 years and is from an open-shelf site off the western Antarctic Peninsula. In past studies, this method of sediment chronology has yielded significantly younger ages than the same cores also analyzed by bulk radiocarbon techniques (Rosenheim, et. al. 2008). Therefore, it is crucial to determine if this method provides a better estimation of sediment age than bulk dating. Since the amount of mixing with differently-aged organic material and sedimentation rates are unknown at each analyzed depth in the core, ramped temperature pyrolysis provides a way to track the specific temperatures at which autochthonous and allochthonous carbon components volatilize. Although this method has shown increased age discrepancy with depth and variable deposition rate in the core, using this more tailored method is likely to produce age estimations for Antarctic samples that will be improved from those approximated by bulk radiocarbon dating.

Rosenheim, Brad E., Mary Beth Day, Eugene Domack, Heather Schrum, Albert Benthien, and John M. Hayes. 2008. Antarctic sediment chronology by programmed-temperature pyrolysis: Methodology and data treatment. G3: Geochemistry Geophysics Geosystems, Vol. 9:1-16.