CAREER: Studies of Magnesium Isotope Geochemistry

元素和同位素在地球上的分布对了解地球的形成和演化具有重要意义。与地球的“积木”，即球粒陨石相比，现在的固体地球是高度不均匀的，具有薄的长质地壳，厚的基性地幔，液体的外核和固体的内核。这些不同的储层之间相互作用的程度以及随时间演变的程度仍然没有得到很好的约束。该奖项旨在通过对镁同位素地球化学的研究，研究地球主要储层之间的起源、演化和相互作用。研究成果将与教育过程相结合，以促进学生的创造力和独立解决问题的能力，通过开发以应用为导向的项目和新的课程设计，扩大参与和增加地球科学本科生的人数，并为更广泛的社区做出贡献。通过最近建立的谷堡州立大学（FVSU）和阿肯色大学（UA）双学位项目合作伙伴关系招收非裔美国学生，为本科生和高中生提供研究机会和夏季研究经验，并为社区大学教师提供专业发展机会。镁同位素地球化学仍处于起步阶段。关于主要固体地球储层的镁同位素组成和高温地质作用中镁同位素分馏程度的研究很少。继PI和其他小组最近对上地壳和地幔地球化学组成的研究之后，建议系统地研究地球主要储层中的Mg同位素变化，并通过研究全球分布的、化学多样性的、特征良好的岩石和矿物来研究可能产生这些变化的过程和机制。研究结果将进一步推动Mg同位素地球化学的发展，为今后将Mg同位素作为壳幔相互作用的示踪剂、火成岩和变质岩的高精度地温测量方法、晶体生长速率、岩浆冷却速率和变质事件的测速仪奠定基础。此外，拟议的研究将使PI首次在阿肯色州建立一个尖端的高温地球化学项目，并帮助UA建立该研究领域的第一个博士项目。CAREER奖将支持一名博士生、一名硕士生和多名本科生，并支持女性和少数族裔在实验室工作（PI实验室的16名学生中有11名是女性，包括一名非洲裔美国人和一名退伍军人）。PI将继续指导国际青年研究人员，支持社区大学教师在实验室工作，并为科学界提供Mg同位素分析服务。建议工作的结果将由学生、博士后和PI在会议和同行评审期刊上报告，并最终引入PI的课程。

The distribution of elements and isotopes in the Earth is important for understanding its formation and evolution. Compared to the 'building blocks' of the Earth, i.e., chondrites, the present solid Earth is highly heterogeneous, with a thin felsic crust, thick mafic mantle, liquid outer core and solid inner core. The extent to which these different reservoirs interacted with each other and evolved over time is still not well-constrained. This CAREER award investigates the origin, evolution and interactions between and among major Earth reservoirs through studies of magnesium isotope geochemistry by graduate and undergraduate students under the mentorship of the PI. The research results will be integrated with the educational process to promote student creativity and independent problem solving abilities, to broaden participation and increase the number of underrepresented undergraduate students in Geosciences and contribute to a broader community, through the development of application-oriented projects and new course design, through recruitment of African American students via a recently installed partnership for a Dual Degree Program between Fort Valley State University (FVSU) and University of Arkansas (UA), by providing research opportunities and summer research experiences for undergraduates and high-school students, and by providing professional development opportunities to community college teachers.Magnesium isotope geochemistry is still in its infancy. Few studies are available on Mg isotopic composition of the major solid Earth reservoirs and the degree to which Mg isotopes can fractionate during high-temperature geological processes. Following recent studies by the PI and other groups on the geochemical composition of the upper crust and the mantle, it is proposed to systematically investigate Mg isotopic variations in major Earth reservoirs and examine the processes and mechanisms that may produce these variations through studies of globally distributed, chemically diverse, well-characterized rocks and minerals. The results of the proposed research will advance the knowledge and state of the art of Mg isotope geochemistry and lay the foundation for using Mg isotopes as a tracer of crust-mantle interaction, as a high-precision geothermometry in igneous and metamorphic rocks, and as a speedometer to constrain the rates of crystal growth, cooling of magma and metamorphic events. Furthermore, the proposed research will enable the PI to establish for the first time a cutting-edge high-temperature geochemistry program at Arkansas and help UA to build the first PhD program in this area of research. The CAREER award will support one PhD student, one master student and multiple undergraduates, and support women and minorities to work in the lab (11 out of 16 students in the PI's lab are female, including one African American and one veteran). The PI will continue mentoring international young researchers, supporting community college teachers to work in the lab and serving the scientific community for Mg isotopic analysis. Results from the proposed work will be reported in conferences and peer-reviewed journals by students, postdocs and the PI, and eventually introduced into the PI's courses.