The School of Earth and Atmospheric Sciences Presents Dr. Cynthia Ebinger, Tulane University
Strain Localization at Cratonic Edges: Constraints from East Africa
Sutures between Archaean cratons and younger orogenic belts represent some of Earth’s largest lateral heterogeneities: > 170 km-thick, buoyant and relatively dry lithosphere juxtaposed to ~100 km-thick, more volatile-rich mantle lithosphere. We use new and existing data from the African continent to examine the role of pre-existing lithospheric thickness and composition variations on the time-space localization of magmatism, faulting, and basin formation.
Seismic tomography and magneto-telluric models, crust and mantle xenolith chemistry, earthquakes, reveal consistent patterns in the style of basin formation and distribution of magmatism. We evaluate models of mantle upwelling beneath a variable thickness lithosphere with spatial variations in the direction and magnitude of seismic anisotropy, which is strongly influenced by mantle flow patterns along lithosphere-asthenosphere topography, fluid-filled cracks, and pre-existing strain fabrics. Enhanced mantle flow and melt extraction at craton edges may localize strain in thick lithosphere, as indicated by energetic lower crust and upper mantle earthquakes.
Thursday, September 17, 2020 - 11:00am to 12:00pm
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Dr. Andrew Newman