Into the icehouse: Dramatic changes at the Devonian-Mississippian Climate Transition (DMCT)

古代海洋温度的重建为未来全球变暖的极限、气候变化的原因以及气候变化对生物多样性的影响提供了重要线索。该项目将测试在早期动物时期热带海洋温度是否非常温暖（35-40°C或95-104°F），并研究快速冷却在引发生物危机中的作用。该研究还将探讨气候变化如何影响钙的循环，以及钙和碳循环之间的联系是否在气候变化中发挥作用。古环境的代理数据将与复杂的质量平衡模型相结合，进一步测试钙、二氧化碳和气候之间的联系。该项目将通过以下方式扩大地球化学教育：(1)培训三名研究生和代表性不足的群体成员掌握尖端技术，(2)为本科生和研究生班开发练习和独立研究项目，以及(3)在每年的TAMU化学开放日举办K-12活动。该项目将通过支持两个尖端质谱系统和共享质量平衡模型框架来加强研究和教育基础设施。该项目将以块状同位素古温学为特色，这是一项最新进展，可测量碳酸盐分子（例如Ca13C18O16O2）中13C和18O的共现。研究人员将对北美（美国和加拿大）和东欧（俄罗斯）保存完好的腕足类动物的壳进行分析，这些壳跨越泥盆纪晚期到密西西比河早期（3.83亿到3.48亿年前），这是一个气候和海洋化学快速变化的时期（“方解石”海洋到“文石”海洋），以及多种生物危机。块状同位素测量将与钙、碳和氧同位素测量以及综合数值模拟相结合，以检查地球历史上这一重大气候变化期间钙、碳和地壳循环之间的相互作用，并促进对不久的将来气候变化后果的更好理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Reconstructions of ancient ocean temperatures give important clues to the limits of future global warming, the causes of climate change, and the impact of climate change on biodiversity. This project will test whether tropical ocean temperatures were extremely warm (35-40 °C or 95-104 °F) during the time of early animals and examine the role of rapid cooling in triggering biotic crises. The study will also explore how climate change impacted the cycling of calcium and whether linkages between the calcium and carbon cycles play a role in climate change. Proxy data for paleoenvironments will be combined with sophisticated mass balance models to further test links between calcium, carbon dioxide, and climate. The project will broaden geochemical education through (1) training of three graduate students and members of underrepresented groups in cutting-edge techniques, (2) development of exercises and independent research projects for undergraduate and graduate classes, and (3) K-12 activities at the annual TAMU Chemistry Open House. The project will enhance research and education infrastructure by supporting two cutting-edge mass-spectrometry systems and by sharing the mass balance model framework.The project will feature clumped isotope paleothermometry, a recent advance that measures the co-occurrence of 13C and 18O in carbonate molecules (e.g., Ca13C18O16O2). Analyses will be performed on well-preserved brachiopod shells from North America (US and Canada) and Eastern Europe (Russia) spanning the Late Devonian to Early Mississippian (383 to 348 million years), a time of rapid climate and ocean chemistry change (“calcite” to “aragonite” seas), and multiple biological crises. Clumped isotope measurements will be combined with measurements of calcium, carbon, and oxygen isotopes and comprehensive numerical modeling to examine the interplay between calcium, carbon, and crustal cycling during this major climatic shift in Earth’s history and foster better understanding of the consequences of climate change in our near future.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.