USING GEOCHRONOLOGY AND ISOTOPE ECOLOGY TO RECONSTRUCT PAST CLIMATES: A CASE STUDY FROM THE MIOCENE SANTA CRUZ FORMATION, ARGENTINA (Invited Presentation)
The MCO is the most recent period of warm, wet conditions in the Cenozoic with atmospheric CO2 concentrations similar to projections of the next decades. SCF sediments span the initiation of the MCO (~17.4 - 16.4 Ma) and offer the opportunity to investigate the response of terrestrial climates to increasing CO2 and global temperatures in a unique, southern high-latitude site. We applied a Bayesian model (modified from “Bchron”) to create an age-depth model for SCF sediments. We propagated model ages and uncertainties onto our stable isotope data using a Monte Carlo method to create a continuous record of mean annual precipitation (MAP) and temperature (MAT) with associated errors. δ13C-based estimates of MAP indicate aridification at the MCO onset before rebounding as global temperatures increased. δ18O-based MAT estimates are high (at least 20°C) and reach ~25°C by 16.4 Ma, about 12 - 17°C warmer than today. Taken together, these data show a more complex manifestation of the MCO in southern Patagonia than recognized elsewhere, and point to the importance of detailed regional studies for better understanding global warming events.