Development of a High-Resolution Paleoclimate Data Set from New Zealand using Speleothem Growth Banding and Stable Isotropic Ratios

Rhawn F. Denniston, Department of Geology, Cornell College

Climatologists have a pressing need for well-dated, high-resolution continental paleoclimatic records in the largely marine Southern Hemisphere.  These data sets are critical for understanding long-term (i.e., glacial-interglacial)  climatic change as well as shorter duration climatic shifts such as those that marked the transitions into and out of the Younger Dryas.  This research proposes to investigate growth banding in New Zealand stalagmites for which coarse stable isotope sequences and high precision mass spectrometry dates have already been obtained (Hellstrom et al., 1998).   Speleothem banding, which has been linked to precipitation, will be documented using CONFOCAL scanning laser microscopy at the University of  Iowa and measured using computer-assisted techniques.  Carbon and oxygen stable isotopic ratios, reflective of temperature and vegetation activity, will be obtained at extremely high temporal resolution for areas of particular interest including the last 1000 years and the Younger Dryas using microsampling and mass spectrometry at the U. Iowa Paul Nelson Isotope Laboratory.