EAR-PF: High-resolution boron isotope variation in marine carbonate fossils: Insights on the timing and mechanisms of Ordovician climate change.

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Dr. Cara K. Thompson has been granted an NSF Earth Sciences Postdoctoral Fellowship to carry out a research and education plan at the State University of New York, Stony Brook. In this study, high-resolution chemostratigraphy of Ordovician marine carbonate platform rocks will be used to understand the ties between climate, perturbations in the marine carbon isotope record and ocean/atmosphere pCO2. The timing and mechanisms behind of the onset of Late Ordovician glaciation are poorly understood, but generally tied to the appearance of large excursions in the marine carbon isotope record. The C-isotope record of the transition between greenhouse climate in the Early to Middle Ordovician to glaciation in the Late Ordovician indicates changes in CO2 drawdown that conflict with sea surface temperature records. These discrepancies highlight the need for a robust proxy for pCO2. The results of this study will represent the earliest record of boron-isotope composition and act as a test for the utility of boron isotope as a proxy for ocean pCO2 in the Paleozoic. Global climate change is a topic high interest in recent decades. Looking to the past record of pCO2 and global climate is essential to predicting the impact of modern changes in atmospheric carbon dioxide concentration on the biosphere. In this study, the boron isotope record, a proxy for marine pCO2, will be extended to early in Earth's history. The Ordovician represents a time of extreme climate change and an interval in which evidence in the fossil record suggests the most rapid biodiversification followed by one of the largest extinction events in Earth's history. This study will provide ample opportunity to engage high school and undergraduate students in active research. Along with students in the Masters of Arts and Teaching program, the PI will incorporate high school students into field exercises, sample processing, and data interpretation. The PI will teach undergraduate and graduate level courses in geochemical records with emphasis on marine carbon, sulfur and oxygen in Earth's history.