[DLS] Manar Al Asad (Harvard)

“Transitions in Earth’s Tectonic Regimes: Causes and Consequences on the Core”

Earth’s mantle occupies most of its volume, connecting the deep, inaccessible core to the surface. Its convection regulates the planet’s temperature, magnetic field, chemical distribution, and, importantly for life, the conditions on the surface. Changes in convective regimes, whether gradual or abrupt, therefore have profound implications for Earth’s evolution and our interpretation of geologic data. I aim to understand transitions in mantle convection regimes: their likelihood and stability, their relationship to magnetic field generation and the challenge of sustaining a long-lived dynamo. In this talk, I will focus on the relationship between Earth’s convective regime and the long-lived geodynamo. I will show that Earth likely operated in a “sluggish-lid” tectonic mode for much of the Precambrian, characterized by partially decoupled mobile plates. This early regime, driven by higher mantle temperatures and the presence of an asthenosphere, moderated core-mantle boundary heat flow, sustaining the geodynamo. This coupled consideration not only explains these two key observations, but also a diverse set of geological observations and are consistent with emerging interpretations of such records.

EAPS Department Lecture Series —

Weekly talks aimed to bring together the entire EAPS community, given by leading thinkers in the areas of geology, geophysics, geobiology, geochemistry, atmospheric science, oceanography, climatology, and planetary science. Runs concurrently with class 12.S501.

Contact: eapsinfo@mit.edu