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.

在古代岩石中的同位素综合和钼将被测量。地球的构建块的源头也随着时间的流逝而变化。关于地球的后期接受历史，以及可能的水和有机分子的来源，这是生命起源的必要条件。从岩石中提取的丁酸和钼的同位素分析将是指代构建块和地球的增生序列的弧度。 Labbrador将分析异常，表明从原始地幔域中衍生。地球历史上有20亿AR。反映了NSF的飞行任务，并使用基金会的智力优点和更广泛的审查标准来获得值得通过评估来支持的支持。