Isabel Montanez, University of California, Davis Vladimir Davydov & Mark Schmitz, Boise State University Chris Poulsen, University of Michigan Neil Tabor, Southern Methodist University Recently developed paleoclimate archives reveal a much more dynamic transition from the late Paleozoic Gondwanan ice age to a greenhouse world than previously considered - one characterized by considerable co-variability in climate and pCO2. Recently documented short-lived (1 to 4 m.y.) episodes of glaciation appear to coincide with large magnitude shifts in atmospheric pCO2, marine and continental temperatures and relative sea-level suggesting a CO2-climate-glaciation link. This link, however, remains untested. We propose an interdisciplinary study focused on significantly improving our understanding of the evolution of the late Paleozoic climate system, and the mechanisms that triggered climate change during the Earth's last period of transition from icehouse to greenhouse states. The research is designed to test two hypotheses: (1) that atmospheric CO2 variability was the primary driver for repeated growth and retreat of continental ice sheets, and, in turn, (2) that late Paleozoic ice sheets strongly influenced global climate, particularly in the tropics. Specific basins in central and eastern Europe and western Argentina have been targeted given their stratigraphic and paleogeographic coverage, presence of marine, paralic and paleosol-bearing terrestrial deposits, and their existing biostratigraphy and potential for further radiometric dating (i.e., multiple intercalated volcanic tuffs) and biostratigraphic analysis. This research has three major objectives: * To establish a radiometrically calibrated, chronostratigraphic framework (Gzhelian to early Middle Permian) through the integration of new and existing bio-, cyclo-, and chemo-stratigraphic (87Sr/86Sr) data with U/Pb dating of volcanic tuffs, and the application of these integrated data to multiple quantitative tools (CONOP, RASC, CASP, GraphCor). * To further develop and calibrate high-resolution, quantitative proxy records of paleo-atmospheric pCO2, paleo-precipitation, and marine and terrestrial paleo-temperatures. This includes critical evaluation and further development of new quantitative proxies as well as direct comparison of proxy records to sedimentologic evidence for glaciations and 'warmings' in southern Gondwanan successions. * Development of a theoretical climate framework for the late Paleozoic glacial-interglacial oscillations using three-dimensional climate models to quantify the sensitivity of ice sheets on Gondwana to pCO2, determine the role of ice sheets in driving global climate change, and make climate predictions that can be tested through comparison with the proxy records. Broader Impacts: The proposed research will offer four major contributions to the broader scientific community: (1) a reconstruction of the late Paleozoic climate system at an unprecedented level of resolution and accuracy, (2) an important test of the pCO2-climate paradigm for climate evolution through Earth history, (3) documentation of marine-terrestrial climate linkages at unprecedented temporal resolution for the Paleozoic, and (4) the first test of proposed correlations of cyclothemic successions in eastern Euramerican and North American basins, and of linkages to the Gondwanan glaciosedimentary record. In addition, to the planned cross-disciplinary training of undergraduate and graduate students, the PIs will integrate their research efforts into three educational outreach programs designed to enhance the research and teaching opportunities of underrepresented undergraduate students and high school science teachers. We will make our data and model simulations available to the greater scientific community by importing them into the CHRONOS System (and its partner website, PaleoStrat), a web-based interactive resource with which PI Davydov is directly involved.
