Collaborative Research: The Zirconium Isotope Composition and Variability of the Silicate Earth -- A Pilot Study

合作研究：硅酸盐地球的锆同位素组成和变化——一项试点研究

基本信息

批准号：
1823748
负责人：
Mauricio Ibanez-Mejia
金额：
$ 30.95万
依托单位：
University of Rochester
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2021-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1823748&HistoricalAwards=false
关键词：
Collaborative Research Zirconium Isotope Composition

项目摘要

Over the past 60 years the element zirconium (Zr) has been increasingly used as a tool for deciphering the differentiation history of the Earth and other 'rocky' planetary bodies in our Solar System. Despite being a 'trace element' (i.e., element of relatively low concentration) in most geological environments, its preferential enrichment in the chemically differentiated portions of the terrestrial planets - like Earth's continental crust - plays a key role in the presence of accessory minerals like zircon (ZrSiO4) and baddeleyite (ZrO2). In addition to being a cornerstone in the study of geologic time using the Uranium-Lead geochronometer, these accessory minerals are the main carriers of zirconium in the crust and are thus likely to preserve a unique yet unexplored record of the evolution of Zr isotope composition through geologic time. As such, understanding the processes that lead to variability in the isotopic composition of zirconium and how this is recorded in Zr-rich accessory minerals, may provide a window to explore the geochemical evolution of our planet in the deep geologic past, even beyond the oldest preserved rock record currently known in our planet.Shifts in the bonding/coordination environment of tetravalent Zr ions in silicate magmas during zircon and baddeleyite crystallization are expected to result in fractionation (i.e., differential equilibrium incorporation) of its isotopes in precipitated solids and residual melts. This implies that small variations in the abundance of zirconium stable isotopes in terrestrial rocks and minerals have the potential to elucidate how this element behaves and fractionates in high-temperature geological environments. This award will support two early-career investigators to develop techniques to measure zirconium isotopic compositions at high precision and explore, for the first time, the stable zirconium isotopic composition of silicate Earth. The principal goals of this research are threefold: 1) To develop the laboratory materials (e.g., isotopic reference standard and isotopic tracers) necessary for making zirconium isotopic measurements at high-precision. This will be accomplished in collaboration with scientist from the National Institute of Standards and Technology (NIST), who in the future will continue to distribute the standard materials produced during this research; 2) To explore the range of variability in zirconium isotopic abundances of key reservoirs that comprise the solid Earth; 3) Using the newly gained knowledge, explore how variations in the isotopic composition of Zr may be linked to the development, evolution and chemical refinement of the Earth's crust.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.

在过去的 60 年里，锆 (Zr) 元素越来越多地被用作破译地球和太阳系中其他“岩石”行星体分化历史的工具。尽管在大多数地质环境中是一种“微量元素”（即浓度相对较低的元素），但它在类地行星（如地球大陆地壳）的化学差异部分中优先富集，在辅助矿物（如锆石（ZrSiO4）和斜锆石（ZrO2）。这些副矿物除了是使用铀-铅地质年代计研究地质时间的基石之外，还是地壳中锆的主要载体，因此可能通过地质时间。因此，了解导致锆同位素组成变化的过程以及如何在富锆副矿物中记录这种变化，可能会为探索地球在深层地质历史中的地球化学演化提供一个窗口，甚至超越最古老的地质历史。目前已知的地球上保存的岩石记录。在锆石和斜锆石结晶过程中，硅酸盐岩浆中四价 Zr 离子的键合/配位环境的变化预计会导致分馏（即微分）沉淀固体和残余熔体中的同位素的平衡结合）。这意味着陆地岩石和矿物中锆稳定同位素丰度的微小变化有可能阐明该元素在高温地质环境中的行为和分馏方式。该奖项将支持两名早期职业研究人员开发高精度测量锆同位素组成的技术，并首次探索硅酸盐地球的稳定锆同位素组成。这项研究的主要目标有三个：1）开发高精度锆同位素测量所需的实验室材料（例如同位素参考标准品和同位素示踪剂）。这将与美国国家标准与技术研究所 (NIST) 的科学家合作完成，他们未来将继续分发本研究期间产生的标准材料； 2）探索构成固体地球的关键储层的锆同位素丰度的变化范围； 3）利用新获得的知识，探索Zr同位素组成的变化如何与地壳的发展、演化和化学精炼联系起来。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准。