Collaborative Research: EAGER: Development of a Method for Paired Potassium/Argon Geochronology and Strontium-Neodymium-Lead Radiogenic Isotope Geochemistry of Dust in Ice Cores

合作研究：EAGER：开发冰芯尘埃配对钾/氩地质年代学和锶-钕-铅放射性同位素地球化学方法

• 批准号: 2032849
• 负责人: Sidney Hemming
• 金额: $ 8.27万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2032849&HistoricalAwards=false
• 关键词: Collaborative; Research; EAGER; Development; Method

Atmospheric dust and sediment serve as valuable tracers of past Earth and ocean processes because their geochemical compositions reflect their bedrock parent material. Scientists use the compositions of sediments and dust as a ‘fingerprint’, linking materials at downstream sites, such as ice and sediment cores, back to their sources. Through geochemical fingerprinting, scientists have gained insight into the causes and impacts of abrupt climate changes, the stability of ice sheets and their potential contributions to sea level rise, and the mechanisms by which ocean and atmospheric circulation patterns change. This project aims to harness the capabilities of two different techniques used to determine sediment provenance. The approach will allow the team to address critical questions regarding past wind patterns around Antarctica, the roles of different dust sources in supplying nutrients to the Southern Ocean, and the behavior of the West Antarctic Ice Sheet during the last interglacial warm period. In addition, the method has the potential to be applied to extraterrestrial materials such as from the Mars Mission and Moon rocks. Geochemical tracing of dust and other sediment sources is a powerful approach that aids in reconstructing past atmosphere, ocean, and ice-sheet dynamics. However, in some regions such as the Southern Hemisphere, even multi-variate approaches such as those using strontium, neodymium, and lead isotopes yield ambiguous results due to overlapping source-area compositions. The team has found that lead isotopes add great value in distinguishing sources and that combining these with potassium/argon geochronology provides significant additional constraints on sediment provenance. The added value is due to the relative ease of resetting potassium/argon ages during subsequent geologic events such as crystallization of new minerals during diagenesis, or by heating, with resetting occurring at lower temperatures than other isotopic systems. The team will develop and test the proposed approach using rock and mineral standards and fine-grained sediments, then apply it to ice-core dust samples from deaccessioned ice cores and dust from the Last Glacial Maximum at key sites. Beyond the broader scientific impact of this new approach, the project will provide opportunities for Colby College undergraduates to experience complete immersion in the world of discovery, working both in Dr. Bess Koffman’s geochemistry lab at Colby and at the Lamont-Doherty Earth Observatory of Columbia University, where they will engage with a wider cohort of students from around the country and have access to state-of-the-art analytical facilities.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.

大气中的灰尘和沉积物是过去地球和海洋过程的宝贵示踪剂，因为它们的地球化学成分反映了他们的基岩父母的材料。科学家将沉积物和灰尘的组成用作“指纹”，将冰和沉积物芯等下游材料（例如冰和沉积物芯）连接到其来源。通过地球化学指纹识别，科学家们深入了解了突然的气候变化的原因和影响，冰盖的稳定性及其对海平面上升的潜在贡献以及海洋和大气循环模式变化的机制。该项目旨在利用用于确定沉积物出处的两种不同技术的功能。该方法将使团队能够解决有关南极周围的风模式的关键问题，不同的尘埃在向南大洋供应养分方面的作用以及在最后一个冰川间温暖时期内的南极冰盖的行为。此外，该方法有可能应用于外星材料，例如来自火星任务和月球岩石。尘埃和其他沉积物来源的地球化学追踪是一种有助于重建过去气氛，海洋和冰上动态的强大方法。但是，在某些地区，例如南半球，甚至是多变量的方法，例如使用锶，新生怪和铅同位素的方法，由于源区域组成重叠而产生模棱两可的结果。该小组发现，铅同位素在区分来源方面增加了巨大的价值，并且将它们与钾/氩气体学结合起来提供了对沉积物出处的重大限制。附加的值是由于随后的地质事件中相对易于重置钾/氩气的相对易于性，例如成岩作用期间新矿物质的结晶或加热，而重置在较低的同位素系统下发生的重置。该团队将使用岩石和矿物标准和细粒沉积物开发和测试拟议的方法，然后将其应用于关键的冰芯中的冰核灰尘样品中，以及从关键地点的最后一个冰川最大值中的灰尘。 Beyond the broader scientific impact of this new approach, the project will provide opportunities for Colby College undergraduates to experience complete immersion in the world of discovery, working both in Dr. Bess Koffman's geochemistry lab at Colby and at the Lamont-Doherty Earth Observatory of Columbia University, where they will engage with a wider cohort of students from around the country and have access to state-of-the-art analytical facilities.This award reflects NSF's法定使命，并使用基金会的知识分子优点和更广泛的影响标准通过评估被认为是宝贵的支持。