Collaborative Research: Deep ocean temperature and continental ice volume from benthic foraminiferal test composition, 77Ma to Present

合作研究：来自底栖有孔虫测试组合物的深海温度和大陆冰量，77Ma 至今

• 批准号: 2302477
• 负责人: Miriam Katz
• 金额: $ 4.86万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-11-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2302477&HistoricalAwards=false
• 关键词: Collaborative; Research; Deep; ocean; temperature

Sea floor sediments record the natural variability of the Earth’s climate system. Studying sediment records can improve our ability to predict how the climate system will respond to human activities. This project will produce records of deep-sea temperatures, continental ice volume, and atmospheric carbon dioxide. The records will document changes in the climate system over the last 77 million years. Those data will improve our understanding of processes such as polar amplification and the ability of the Earth’s system to adjust to different atmospheric carbon dioxide concentrations. This study will also improve our knowledge of long-term changes in deep ocean temperatures and ice-sheet volume variability and their connection to changes in atmospheric carbon dioxide. The project will be carried out by two female scientists, one of whom is an early career researcher. Several undergraduate and graduate students will participate to the proposed research activities. The outreach program will involve Earth/Environmental Science teachers from middle and high schools. Benthic foraminifera are excellent recorders of past environmental conditions. In particular, the benthic foraminiferal (bf) magnesium/calcium ratio (Mg/Ca) is used as a temperature proxy, making it possible to separate temperature from ice volume effects on the widely used bf oxygen isotope proxy (d18O). However, the bf Mg/Ca signal is complicated by a dependency on carbonate saturation state (“omega”) in addition to temperature. Benthic foraminiferal lithium, boron and strontium to calcium ratios (Li-B-Sr/Ca) show promise in separating the temperature and omega contributions to bf Mg/Ca. The proposed research will: 1) construct robust temperature and ice volume histories during the late Cretaceous and Cenozoic (~77-0 Ma) using bf d18O in conjunction with bf Mg-Li-B-Sr/Ca; and 2) calibrate offsets in bf Mg-Li-B-Sr/Ca for multiple species across paleodepth transects to encompass a range of omega. Different species’ physiological response to variations in temperature, omega, and seawater element/Ca ratios will be addressed using a multivariate model. One-Myr sample spacing will be used for the calibrations, whereas a new higher-resolution (~200 Kyr) record will provide a robust dataset of bf Mg/Ca variations since 77 Ma. This dataset will be used, together with bf d18O data, to test the hypothesis that deep ocean temperature and continental ice volume covary from the Late Cretaceous to the Cenozoic. The connections among changes in deep ocean temperature (and chemistry), continental ice volume, and atmospheric carbon dioxide concentration will be investigated using a numerical box model of the ocean carbon cycle.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.

海底沉积物记录了地球气候系统的自然变化。研究沉积物记录可以提高我们预测气候系统如何响应人类活动的能力。该项目将记录深海温度、大陆冰量和大气二氧化碳。这些记录将记录过去7700万年来气候系统的变化。这些数据将增进我们对极地放大等过程的了解，以及地球系统适应不同大气二氧化碳浓度的能力。这项研究还将增进我们对深海温度和冰盖体积变化的长期变化及其与大气二氧化碳变化的联系的了解。该项目将由两名女科学家执行，其中一名是早期职业研究人员。一些本科生和研究生将参加拟议的研究活动。该推广计划将涉及来自初中和高中的地球/环境科学教师。底栖有孔虫是过去环境条件的优秀记录者。特别是，底栖有孔虫（BF）镁/钙比（Mg/Ca）被用作温度代理，使人们有可能从冰量的影响，广泛使用的BF氧同位素代理（d18 O）分离温度。然而，由于除了温度之外还依赖于碳酸盐饱和状态（“ω”），bf Mg/Ca信号变得复杂。底栖有孔虫的锂，硼和锶钙比（Li-B-Sr/Ca）显示分离的温度和欧米茄的贡献BF镁/钙的承诺。拟议的研究将：1）使用bf d18 O结合bf Mg-Li-B-Sr/Ca构建晚白垩世和新生代（~77-0 Ma）期间稳健的温度和冰量历史; 2）校准跨古深度断面的多个物种的bf Mg-Li-B-Sr/Ca中的偏移，以涵盖一系列Ω。不同物种的生理反应的变化，温度，ω和海水元素/钙的比例将使用多变量模型。一个百万年的样本间隔将用于校准，而一个新的更高分辨率（~200千年）的记录将提供一个强大的数据集高炉镁/钙变化，因为77马。该数据集将被用来，与BF d18 O数据，以测试的假设，深海温度和大陆冰量协变从晚白垩世到新生代。利用海洋碳循环的数值箱模型研究深海温度（和化学）、大陆冰量和大气二氧化碳浓度变化之间的联系。该奖项反映了NSF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。