Collaborative Research: From Silicate Melts Properties to the Dynamics and Evolution of an Early Basal Magma Ocean

Collaborative Research: From Silicate Melts Properties to the Dynamics and Evolution of an Early Basal Magma Ocean Collaborative Research: From Silicate Melts Properties to the Dynamics and Evolution of an Early Basal Magma Ocean Overview There is no unifying theory for the thermal evolution of the Earth which can reconcile disparate observations from seismology, geochemistry, geodynamics, and geomagnetism. Geochemical signatures of volcanic rocks indicate the existence of large, deep structures that have maintained primordial chemical signatures since early in Earth history. Understanding the nature and origin of these geochemical reservoirs is fundamental to constraining the Earths energy budget and thermochemical evolution of the mantle. One hypothesis for a process that generates Fe-enrichment in the lower mantle is that of a basal magma ocean (BMO). This collaborative proposal will study the potential role of basal BMO in influencing early Earth geodynamo processes through the combination of state-of-the-art measurements on Fe-bearing molten silicates comprised of dynamic compression experiments led by PIs Mao and Gleason, static compression experiments led by PI Shim, and geodynamic modeling led by PI Stegman. Intellectual merit: We will collect new measurements on the physical properties of molten, Fe-bearing silicates to which represent crucial experimental constraints for modeling on the dynamics and evolution of an early basal magma ocean. These properties include Fe-spin state (which has only recently become feasible for high pressure melts), density, structure, and partitioning will allow us to better understand how BMOs have affected the evolution of Earth's magnetic field and possibly powering the geodynamo. This will be accomplished by supplying new geodynamic models for BMOs with relevant, high-pressure, -temperature physical properties of constituent materials. Our proposal will focus on experimental studies combined with geodynamic modelling to address outstanding questions about the evolution of a basal magma ocean and energy for powering an early dynamo. This work will address several thrusts in the 2016 CSEDI Community document: Understanding the Origin and Evolution of our Planet Through Interdisciplinary Research in the themes of Early Earth: Formation and Evolution, Magma Ocean and Core Formation, and Origin of the Geodynamo, and is poised to answer the first question in the recent National Academies report: A Vision for NSF Earth Sciences 2020-2030: Earth in Time regarding How is Earths internal magnetic field generated?.This work represents a new, multidisciplinary collaboration between experimental mineral physics and computational geodynamics to advance our understanding of deep and early Earth processes. This is the first proposal among this group of researchers. PI Stegmann has not previously collaborated with PIs Mao, Gleason, and Shim. Broader impact: The success of this proposal depends on the participation of young, diverse researchers, and the PIs are committed to supporting their career development. They will be exposed to collaborative science and a broader range of research than would be possible for an individual PI project. This work will support training of graduate students in a variety of dynamic and static compression techniques and X-ray and in-house characterization tools at unique world-class facilities as well as how to develop and refine models of planetary interiors that use the experimental constraints. Another key component of our broader impacts is that each year we will be providing research experiences to undergraduate and highschool interns. We will use a cohort-building model with multiple layers of support and mentoring. We will disseminate our results in a timely manner through presentations at national and international meetings/conferences/workshops and publications. The PIs recognize the need to share our understanding of the Earth with the broader community. In terms of outreach to the general public, we continue to be active in looking for opportunities to publicize our work by partnering with the communications and press offices at Stanford/SLAC, ASU, and UCSD. In addition, we anticipate the technical advancements which are a byproduct of this work will be useful to other experimentalists including high-pressure physicists, chemists, and materials scientists engaging in fundamental and applied research who wish to conduct these types of measurements on a wider range of materials.