CSEDI Collaborative Research: The nature and timing of Earth's accretion

CSEDI 合作研究：地球吸积的性质和时间

• 批准号: 2054884
• 负责人: Sujoy Mukhopadhyay
• 金额: $ 20.71万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2054884&HistoricalAwards=false
• 关键词: CSEDI; Collaborative; Research; nature; timing

The Earth formed by a series of collisions between smaller rocky bodies. At some point during this process, the Earth also acquired the elements, known as volatiles, that make up its atmosphere and oceans. But how and when the Earth formed, and how and when it acquired its volatiles, are still very uncertain. This matters, because the volatile elements are essential for life as we know it; if we can understand how the Earth acquired its volatiles, that will help us understand how other planets did so, in this solar system and elsewhere. To solve this problem the investigators use two main tools. One is a series of natural “clocks”, derived from radioactive elements that decay; these tell us how fast things happened. The second is experiments to determine whether the volatile elements were sequestered into the Earth’s iron core, or whether they were left behind in the rocks and atmosphere. As part of this investigation the team will train graduate and undergraduate students – some from under-represented minorities - in experimental and analytical techniques, adding to the technically-trained workforce.In this proposal the investigators explore the combined effects of volatile loss and core sequestration on a range of moderately volatile and refractory elements. They will use four isotopic chronometers (Hf-W, Pd-Ag, U-Pb and I-Pu-Xe), with different half-lives and chemical characteristics, to disentangle these two effects. The modeling efforts use N-body accretion models, allowing provenance to be tracked and isotopic evolution to be tracked; they also propose to carry out necessary experimental measurements on partitioning behavior and mantle Xe isotopic compositions. The team will use the four isotopic systems to answer three major questions: 1) are the Grand Tack or conventional accretion scenarios more consistent with the observations? 2) how did the composition of material added to the Earth change as accretion proceeded?; 3) how much volatile loss happened during and after accretion itself? In answering these questions the investigators will provide a more focused picture of the formation and earliest evolution of the Earth. The proposed research involves an inter-disciplinary collaboration between a modeler, an isotope geochemist and a high-pressure mineralogist. As such, it cuts across traditional disciplinary boundaries and will provide an opportunity for the three groups to educate each other and integrate experiments, measurements and modeling.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.

地球是由较小的岩石体之间的一系列碰撞形成的。在此过程中的某个时候，地球还获得了构成其大气和海洋的元素，称为挥发物。但是，地球如何以及何时形成，如何以及何时获得挥发物，仍然非常不确定。这很重要，因为挥发性元素对我们所知的生命至关重要。如果我们能够理解地球如何获得其挥发物，那将有助于我们了解其他行星在太阳系和其他地方的挥发物。为了解决这个问题，研究人员使用了两个主要工具。一个是一系列自然的“时钟”，源自腐烂的放射性元素。这些告诉我们事情发生了多快。第二个是确定挥发性元件是否被隔离到地球铁芯中的实验，还是将它们留在岩石和大气中。作为这项投资的一部分，该团队将在实验和分析技术中培训毕业生和本科生（一些来自代表性不足的少数群体的人），这增加了技术训练的劳动力。在本提案中，研究人员探索了研究人员探索波动性损失和核心损失和核心损失对中等易发生和逆性元素的影响。他们将使用四个具有不同半衰期和化学特征的同位素天文组织（HF-W，PD-AG，U-PB和I-PU-XE）来解散这两种效果。建模工作使用N体积聚模型，可以跟踪出处并跟踪同位素进化；他们还建议对分配行为和地幔XE同位素组成进行必要的实验测量。该团队将使用四个同位素系统回答三个主要问题：1）大钉或传统积聚方案是否与观察结果更一致？ 2）随着积聚的进行，添加到地球中的材料的成分如何变化？ 3）在积聚本身和积聚之后发生了多少挥发性损失？在回答这些问题时，调查人员将为地球的形成和最早的发展提供更集中的画面。拟议的研究涉及建模者，同位素地球化学家和高压矿物学家之间的跨学科合作。因此，它跨越了传统的纪律界限，并将为这三个小组提供一个相互教育和综合实验，测量和建模的机会。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和更广泛的影响标准通过评估来获得的支持。