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

卡拉·K·汤普森博士获得了美国国家科学基金会地球科学博士后奖学金，将在纽约州立大学石溪分校开展一项研究和教育计划。在这项研究中，将利用奥陶系海相碳酸盐台地岩石的高分辨率化学地层学来了解气候、海洋碳同位素记录的扰动和海洋/大气二氧化碳之间的联系。晚奥陶世冰川作用开始的时间和机制尚不清楚，但通常与海洋碳同位素记录中出现的大漂移有关。从早奥陶世到中奥陶世温室气候向晚奥陶世冰川转变的碳同位素记录表明，二氧化碳下降的变化与海表面温度记录相冲突。这些差异突显出需要一个可靠的二氧化碳替代指标。这项研究的结果将是对硼同位素组成的最早记录，并将测试硼同位素作为古生代海洋二氧化碳分压的替代物的实用性。全球气候变化是近几十年来备受关注的话题。查看过去二氧化碳浓度和全球气候的记录，对于预测大气二氧化碳浓度的现代变化对生物圈的影响至关重要。在这项研究中，代表海洋二氧化碳的硼同位素记录将延伸到地球历史的早期。奥陶纪代表了极端气候变化的时期，化石记录中的证据表明，在这段时间里，生物多样性最快，随后发生了地球历史上最大的物种灭绝事件之一。这项研究将提供充分的机会让高中生和本科生参与积极的研究。与艺术与教学硕士课程的学生一起，PI将让高中生参与实地练习、样本处理和数据解释。PI将教授本科生和研究生水平的地球化学记录课程，重点是地球历史上的海洋碳、硫和氧。

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.