Study of Mass Independent Isotopic Compositions of Ru and Mo in Early Earth Rocks

早期地球岩石中钌和钼的质量独立同位素组成研究

• 批准号: 2020029
• 负责人: Richard Walker
• 金额: $ 31.74万
• 依托单位: University of Maryland, College Park
• 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: 2020-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2020029&HistoricalAwards=false
• 关键词: Study; Mass; Independent; Isotopic; Compositions

The isotopic compositions of ruthenium and molybdenum in ancient rocks will be measured. So-called mass-independent variations in the isotopic compositions of these elements can reveal the cosmochemical “genetics” of planets; i.e., what they were made from. In the case of Earth, some evidence suggests the genetic signatures of these elements may have changed with time as the planet accreted, indicating that the sources of Earth’s building blocks also changed with time. The objective of this study is to ascertain the level of isotopic heterogeneity present in rocks more than 2.5 billion years old. The isotopic differences in these elements in early-Earth rocks, compared to modern rocks, will provide new insights with regard to the late stage accretionary history of Earth, as well as possible sources of water and organic molecules that were the necessary ingredients for the origin of life. This project will support a postdoctoral associate to conduct state-of-the-art research and will also involve contributions from an undergraduate as part of a senior thesis project.High-precision isotopic analysis of ruthenium and molybdenum extracted from Archean rocks will be conducted. The specific objective will be to identify and interpret genetic (nucleosynthetic) characteristics of early Earth rocks, particularly with respect to characterizing the building blocks and accretionary sequence of planet Earth. Using proven techniques including nickel-sulphide fire assay pre-concentration, chemical purification and thermal ionization mass spectrometry, Archean rocks from southwestern Greenland, as well as Eoarchean rocks from Nuvvuagittuq (Quebec), and Saglek (Labrador) will be analyzed. Most of these rocks are characterized by positive 182W anomalies, indicative of derivation from primordial mantle domains. Further, we will analyze rocks from three suites of Archean komatiites, also characterized by 182W. The results of this project will provide important information about the accretionary history of Earth. Consequently, it will advance our understanding of the events leading to the creation of a habitable planet, as well as provide clues to the evolution of the mantle during the first 2 billion years of Earth history. Findings will guide dynamical modelers of both the early Solar System evolution and the early mantle. This project will support a postdoctoral associate to conduct state-of-the-art research and will also involve contributions from an undergraduate as part of a senior thesis project.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.

将测量古代岩石中ruthenium和钼的同位素组成。这些元素的同位素组成中所谓的质量非依赖性变化可以揭示行星的宇宙化学“遗传学”。即，它们是由什么制成的。在地球的情况下，一些证据表明，随着地球的接受，这些元素的遗传特征可能随着时间而变化，表明地球的构件来源也随着时间的流逝而改变。这项研究的目的是确定超过25亿年历史的岩石中存在的同位素异质性水平。与现代岩石相比，这些元素在这些元素中的同位素差异将就地球的后期增生历史以及可能的水和有机分子的来源提供新的见解，这是生命起源的必要物质。该项目将支持博士后助理进行最先进的研究，并将涉及本科生的贡献，作为高级论文项目的一部分。将进行从Archean Rocks中提取的High Precision同位素分析和钼的同位素分析。具体目标是识别和解释早期地球岩石的遗传（核合成）特征，尤其是在表征地球的构建块和增生序列方面。使用经过验证的技术，包括镍硫化物消防测定预浓度，化学纯化和热电离质谱，来自西南格陵兰岛的Archean Rock以及Nuvvuagittuq（Quebec）和Saglek（Labrador）的Eoarchen Rocks。这些岩石中的大多数的特征是阳性182W异常，表明是从原始地幔结构域推导的。此外，我们将分析三个套房的岩石，其岩石的岩石也以182W为特征。该项目的结果将提供有关地球增生历史的重要信息。因此，它将促进我们对导致居住星球创造的事件的理解，并在地球历史的前20亿年内为地幔的演变提供线索。发现将指导早期太阳系演化和早期地幔的动态建模者。该项目将支持博士后助理进行最先进的研究，并将涉及本科生的贡献，作为高级论文项目的一部分。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛的影响审查标准通过评估来获得的支持。