Spatiotemporal Variability of Tungsten-182 in the Hawaiian Plume

夏威夷羽流中钨 182 的时空变化

• 批准号: 2121979
• 负责人: Richard Walker
• 金额: $ 38.37万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2121979&HistoricalAwards=false
• 关键词: Spatiotemporal; Variability; Tungsten; 182; Hawaiian

The isotopic composition of the element tungsten is important to measure in some types of volcanic rocks because differences in the abundance of the isotope of tungsten-182 occurred very early in the history of the Earth due to the radioactive decay of an isotope of another element, hafnium-182. Hafnium-182 was present in our solar system for only about the first 70 million years of its history. This means that some of the magmas that crystallize to form volcanic rocks came from places within the Earth’s mantle that formed more than 4 billion years ago and that did not mix with other mantle rocks. For this study the isotopic composition of tungsten will be measured in rocks from the Hawaiian Islands. Studies have shown that the isotopic composition of tungsten in rocks from volcanic oceanic islands like the Hawaiian Islands varies. Tungsten isotopic variations that will be measured by this study will provide important new information about how the Earth formed and separated into a metal core, and silicate mantle and crust. The information will also provide hints about where these old parts of the mantle may be and how they end up in volcanic rocks. The results will give scientists who model the movement of rocks and melts in the mantle new insights about how the Earth currently cools itself from the inside out. This project will support a Ph.D. student and a postdoctoral Research Associate to conduct most of the, and will also involve contributions from an undergraduate student as part of a senior thesis project. High-precision isotopic analysis will be conducted on tungsten extracted from a suite of carefully chosen Hawaiian lavas that, based on long-lived radiogenic isotope systems and trace element abundances. The University of Maryland laboratory has been a world leader in tungsten isotope research of this type over the past decade. The various geochemical signals have previously been interpreted to sample various recycled and deep mantle components. Prior work on ocean island basalts, as well as other types of rocks (young and old), has demonstrated the laboratory’s capability to cleanly separate tungsten from rocks, and generate highly-precise isotopic measurements using thermal ionization mass spectrometry. The primary objective of this study will be to identify and interpret small tungsten isotopic “anomalies” and attempt to relate the anomalies to other geochemical tracers, such as Nd, Pb and Os isotopic composition, potentially allowing connections to be made between the timing and nature of both early Earth processes, such as magma ocean formation and core separation, as well as ongoing processes within the modern mantle.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.

在某些时间类型的火山岩中，钨的同位素组成是因为辅助的差异在某种程度上出现在另一种元素的放射性衰变的历史中，这是另一个元素-182中存在的同位素的历史。太阳能太阳能系统仅用于7000万个帽子的帽子来自夏威夷群岛的岩石中的钨在岩石中的同位素成分各不相同在那里提供这些地幔的OLT，以及在火山岩石中的最终结果。与大多数人一起涉及ANN本科生的贡献，这是THE THE THE THE THES THES THE THE IS PROVECT长期寿命的放射性同位素系统和痕量元素丰度。岛玄武岩以及其他类型的岩石（年轻人和老式）已经证明了实验室从岩石中清洁钨的能力，并使用这项研究的主要目标是使用热液化的同位素测量。解释小钨同位素“异常”，并试图将异常与其他地球形示踪剂联系起来，具有ND，PB和OS同位素组成，可能允许在两者之间既早些时候早起又有两者的时间和性质之间建立连接。过程，例如岩浆海洋形成和核心分离以及Ondr Ission，被认为值得通过评估的智力优点和更广泛的影响来获得支持的氛围。