EAR-PF: Testing if the SPICE is right - disentangling diagenesis, seawater chemistry, and ecological change across Cambrian trilobite extinctions using Ca and Mg isotope ratios

EAR-PF：测试 SPICE 是否正确 - 使用 Ca 和 Mg 同位素比率解开寒武纪三叶虫灭绝过程中的成岩作用、海水化学和生态变化

• 批准号: 2204376
• 负责人: Preston Kemeny
• 金额: $ 18万
• 依托单位: Kemeny, Preston Cosslett
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2204376&HistoricalAwards=false
• 关键词: EAR; PF; Testing; SPICE; right

Dr. Preston Cosslett Kemeny has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out research, professional development, and outreach activities at the University of Chicago under the mentorship of Dr. Clara Blättler. In this project, Dr. Kemeny will investigate the relationship between trilobite extinction and seawater chemistry during the Cambrian Period (approximately 540 to 485 million years ago). This work has broad implications for establishing robust environmental and ecological policy in the coming decades because understanding the interwoven nature of ancient life and climate provides fundamental context for predicting and responding to anthropogenic climate change. Previously, many interpretations of chemical variability in rocks implicated causal linkages between the global carbon cycle and ecological turnover. However, recent developments in the study of sedimentary processes have suggested that extinction and diversification may only weakly relate to environmental perturbations. The Cambrian Period offers unique opportunities for testing connections between ecology and seawater chemistry because it contains multiple trilobite extinction and diversification intervals associated with chemical anomalies. In this work, Dr. Kemeny will perform geochemical measurements on Cambrian rocks and fossils, and synthesize those observations within a numerical model, to better understand the relationship between extinction and the global carbon cycle. In addition, Dr. Kemeny will continue efforts to create an inclusive community through research, teaching, mentorship, and service activities that increase diversity, equity, inclusivity, and accessibility in the geosciences. These activities will include mentoring undergraduate and graduate students, training in effective and inclusive pedagogy, and working with local teachers to develop publicly available lesson plans on the global carbon cycle and paleontology.This project will study the coevolution of life with climate by quantifying connections between the global carbon cycle and trilobite extinction during the Cambrian Period. Dr. Kemeny will (1) measure calcium and magnesium isotope ratios in drill core samples from the Missouri basin to determine whether the Cambrian Steptoean Positive Carbon Isotope Excursion (SPICE) reflects a shift in the marine 13C/12C ratio or a shift in either the style of post-depositional alteration or mineralogy, (2) test existing hypotheses of marine anoxia during the SPICE event using sulfur and uranium isotope ratios, (3) evaluate trilobite fossils as a novel proxy for diagenetic modification and seawater chemistry, and (4) reproduce the isotopic observations within a box model of the ocean-atmosphere system and numerically constrain the temporal and spatial scales over which diagenesis can produce carbon isotope excursions. By disentangling biodiversity change from environmental change during the SPICE event, this project will take concrete steps towards understanding the coevolution of life with climate. Furthermore, by exploring a trilobite-based proxy for diagenetic alteration, the proposed work may provide a new tool to the geochemical community for reconstructing marine chemistry and for studying connections between the global carbon cycle and ecological turnover throughout the Paleozoic.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.

Preston Cosslett Kemeny博士在ClaraBlättler博士的心态下被授予NSF地球科学博士后奖学金，以在芝加哥大学进行研究，专业发展和外展活动。在这个项目中，凯门尼博士将调查寒武纪时期三叶虫扩展与海水化学之间的关系（约540至4.85亿年前）。这项工作对在未来几十年中建立强大的环境和生态政策具有广泛的影响，因为了解古代生活和气候的交织性质为预测和应对人为气候变化提供了基本背景。以前，对岩石中化学变异性的许多解释都在全球碳循环和生态周转之间实现了催化连接。但是，沉积过程研究的最新发展表明，扩展和多样化可能仅与环境扰动无关。寒武纪时期为测试生态学与海水化学之间的连接提供了独特的机会，因为它包含了多个与化学异常相关的三叶虫扩展和多元化间隔。在这项工作中，凯梅尼博士将对寒武纪岩石和化石进行地球化学测量，并在数值模型中综合这些观察结果，以更好地了解扩展与全球碳循环之间的关系。此外，凯门尼（Kemeny）博士将继续努力通过研究，教学，心态和服务活动来建立一个包容性社区，从而增加地球科学中的多样性，公平，包容性和可及性。这些活动将包括心理本科生和研究生，有效和包容性教学法的培训，以及与当地教师合作制定有关全球碳循环和古生物学的公开课程计划。该项目将通过量化剑术期间的全球碳循环和trilobite之间的连接来研究生活与气候的同步。 Kemeny博士（1）测量来自密苏里盆地的钻头样品中的钙和镁同位素比，以确定寒武纪的Steptoean阳性碳同位素偏移（SPICE）是否反映了海上13c/12c的比例的变化，还是在使用硫磺后或Minerolotic（2）在现有的硫磺时（2）spece spece and sasse and sasse and sasse and sasse and sasse and sasse（2）sprice and sasse（2）铀同位素比，（3）评估三叶岩化石作为诊断修饰和海水化学的新型代理，以及（4）在海洋 - 大圈系统的盒子模型中重现同位素观测，并在数值上限制了临时和空间尺度，从而产生了临时和空间量表，从而产生了碳质量的excorpersions。通过在香料事件期间，将生物多样性从环境变化中脱颖而出，该项目将采取具体的步骤来理解与气候的生命相结合。此外，通过探索基于三叶岩的诊断更改的代理，拟议的工作可以为地球化学社区提供一个新的工具，用于重建海洋化学，并研究全球碳循环与生态转移之间的联系和整个古生物的生态转移之间的联系。这一奖项反映了NSF的法定任务和审查的良好态度，这是通过评估构成的构成的构成范围，这是通过构成的支持。