EAGER: Collaborative Research: Collaborative Investigations of Isotopic Fractionation by Thermal Diffusion and Thermal Migration

EAGER：协作研究：通过热扩散和热迁移进行同位素分馏的协作研究

• 批准号: 0944238
• 负责人: James Van Orman
• 金额: $ 5.97万
• 依托单位: Case Western Reserve University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0944238&HistoricalAwards=false
• 关键词: EAGER; Collaborative; Research; Investigations; Isotopic

This EArly-concept Grant for Exploratory Research (EAGER) represents an interdisciplinary effort to address the geochemical processes that could be responsible for recent observations of stable isotope variations for "non-traditional stable isotopes" in igneous rocks (NTSI). Significant fractionations in the isotopes of Mg and Si are difficult to explain in terms of equilibrium between minerals and their melts during common igneous differentiation processes. The exciting new discovery that large isotopic fractionations occur in melts held within a temperature gradient offers a possible explanation for the observed isotope variations. The fractionation by thermal diffusion is so large that it may provide the basis for a unique tool to discern the role of thermal-gradient-driven processes for magmatic differentiation. This project represents a synergistic and novel collaboration that brings experimental, analytical, and theoretical approaches to the study of this NTSI fractionation phenomenon. Three complementary efforts will be undertaken that include: 1) Laboratory silicate Soret (fully molten) experiments using both natural compositions and selected simple systems; 2) Analysis of major and trace element behavior and NTSI fractionation in thermal migration (partially molten) experiments on basalt to rhyolite bulk compositions and determination of BetaT for Mg, Si and Fe; and 3) Molecular dynamics simulations of isotope fractionation within a temperature gradient in the MgO-SiO2 system to investigate the physical basis for the effects of thermal diffusion on NTSI fractionation. The proposed science plan brings together three groups of researchers with different expertises in petrology/geochemistry research from field petrology to experimental petrology to molecular dynamics simulation.

这项对探索性研究的早期概念赠款（急切）代表了解决地球化学过程的跨学科努力，该过程可能导致最近观察到稳定的同位素变化“非传统稳定同位素”（NTSI）的“非传统同位素”。在常见的火成岩分化过程中，很难用Mg和Si同位素的显着分馏。令人兴奋的新发现，即在温度梯度内保持的熔体中发生了大型同位素分馏，这为观察到的同位素变化提供了可能的解释。热扩散的分馏非常大，以至于它可以为识别热梯度驱动过程的岩浆分化过程的作用提供唯一工具的基础。该项目代表了一种协同和新颖的合作，该合作将实验，分析和理论方法带入了这种NTSI分馏现象的研究。将进行三项互补工作，其中包括：1）使用天然组成和选定的简单系统实验室硅酸盐Soret（完全熔融）实验； 2）分析在玄武岩到流纹岩体组成的热迁移（部分熔融）实验中的主要元素行为和NTSI分馏，并确定MG，SI和FE的BETAT； 3）MGO-SIO2系统中温度梯度内同位素分馏的分子动力学模拟，以研究热扩散对NTSI分馏的影响的物理基础。拟议的科学计划汇集了从岩石学到实验质学到分子动力学模拟的三组研究人员，在岩石学/地球化学研究方面具有不同的专业研究。