CAREER: Studies of Magnesium Isotope Geochemistry

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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.