CSEDI Research: Fine Structure of the Lower Mantle

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Gurnis, Michael EAR-0001966 This is a renewal of a collaborative project in which a seismologist and a geodynamicist (with their students) work closely together to understand the dynamics and fine structure of the lower mantle. The investigators have focussed on this region of the deep Earth because it plays such an important role in controlling the thermal and chemical state and evolution of the entire planet. In this project, seismological and geodynamical methodologies are tightly integrated. Geodynamical models (some integrated to the geological evolution of surface plates) are used to study: The dynamics of upwelling regions with large variations in viscosity, partial melting, and chemical heterogeneity; strong, cold slabs interacting with thermo-chemical boundary layers; and lateral transition regions between upwellings and downwellings. These thermo-chemical structures are mapped into two- and three-dimensional seismic velocity fields so that dynamic models are directly tested against observed waveforms, differential travel times, and tomography. The dynamic models motivate the collection of new data while also suggesting new ways to interpret seismic models. This approach has lead to an acceleration in our understanding of Earth processes.