Events

Speaker: Kate Rychert, Associate Scientist, Woods Hole Oceanographic Institution

Host: Thorsten Becker

Title: A dynamic lithosphere-asthenosphere boundary: the PI-LAB experiment

Abstract: Plate tectonics revolutionized our understanding of how the Earth works, providing a framework for volcanism, earthquakes, continental formation and breakup and the geologic record of climate change. Yet, what makes a plate “plate-like” and where and how the rigid lithospheric plate transitions to the underlying weaker asthenosphere are widely debated. I present new geophysical constraints on the LAB from the PI-LAB (Passive Imaging of the LAB) experiment using a range of methodologies, techniques, and resolutions in one location near the equatorial Mid-Atlantic Ridge. We find that the LAB has a variable character depending on location: simple, with monotonic age progression, undulating, and underlain by a thin melt channel. The result reconciles seemingly discrepant and variable reports of the LAB and partial melt from previous studies. Putting the LAB result from the Mid-Atlantic Ridge in the context globally, in particular, by considering a new interdisciplinary compilation of LAB depths, suggests that temperature determines the thickness of the plate to first order. However, the LAB is dynamic. Composition, in addition to melt generation and migration also affect the depth and definition of the LAB and likely play a role in driving plate tectonics.