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The Asthenosphere, Mantle Convection, and the Dynamics of Plate Tectonics

Adrian Lenardic (Department of Earth Science, Rice University)
Fri, April 6, 2018, 10:30am - 11:30am

Video Broadcast

Host: Thorsten Becker

Since the discovery of plate tectonics it has been suspected, but never fully demonstrated, that a low-viscosity layer beneath the plates (i.e., the asthenosphere) may play a central role in facilitating their motions. This idea has cast a significant shadow not only on Earth dynamics but also on comparative planetology - in particular on Earth-Venus comparisons. We review constraints on the structure and viscosity of the asthenosphere that are provided by geoid and post glacial rebound studies. We also review previous numerical simulations that highlighted the potentially key role that a rheologically weak asthenosphere, interacting with plates above, could play in maintaining plate tectonics on Earth. We then present new models that expand explorations into the defining characteristics of the asthenosphere and its role for the mantle convection and plate tectonics. The collective works leads us to suggest a geodynamic definition of the asthenosphere that breaks from the traditional view that the principal role of the asthenosphere, for plate tectonics, is to provide basal lubrication for plates.