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

测定了古岩石中钌和钼的同位素组成。这些元素的同位素组成中所谓的质量独立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，这些元素的遗传特征可能随着时间的推移而改变，这表明地球的构建块的来源也随着时间的推移而改变。这项研究的目的是确定超过25亿年的岩石中存在的同位素不均匀性水平。与现代岩石相比，早期地球岩石中这些元素的同位素差异将为地球晚期增生历史以及生命起源所必需的水和有机分子的可能来源提供新的见解。该项目将支持一名博士后助理进行最先进的研究，并将涉及一名本科生的贡献，作为高级论文项目的一部分。将对从太古代岩石中提取的钌和钼进行高精度同位素分析。具体目标将是确定和解释早期地球岩石的遗传（核合成）特征，特别是在描述地球的组成部分和增生序列方面。将使用已得到证实的技术，包括硫化镍火试金预浓缩、化学纯化和热电离质谱法，对格陵兰西南部的太古代岩石以及Nuvvuagittuq（魁北克）和Saglek（拉布拉多）的始新世岩石进行分析。这些岩石中的大多数具有182 W正异常的特征，表明其源自原始地幔域。此外，我们将分析三套太古代科马提岩的岩石，也具有182 W的特征。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创建可居住行星的事件的理解，并为地球历史最初20亿年期间地幔的演变提供线索。这些发现将指导早期太阳系演化和早期地幔的动力学模型。该项目将支持一名博士后进行最先进的研究，也将涉及一名本科生的贡献，作为高级论文项目的一部分。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.