207-8 From Rift to Rupture: Strain Localization Mechanisms and the Path to Late-Stage Continental Rifting, with or without Magma

Session: Honoring the Late Professor Mohamed Abdelsalam: Outstanding Researcher, Generous Colleague, Legendary Mentor, and Ambassador for the Geosciences In Africa

Presenting Author:

Author:

Abstract:

The fate of actively extending continents hinges on sustained and persistent accommodation and localization of strain in the lithosphere, starting first at the rift initiation phase, continuing through the rift maturation phases to late-stage extension and breakup phases. Despite decades of geological and geophysical investigations into the evolution of continental divergent plate boundaries, some key knowledge gaps remain on how rifts initiate and establish themselves as distinct divergent plate boundaries, as well as on how they evolve through the maturation phases. More specifically, how and where incipient continental rifts become border-faulted to establish the plate boundary, and what mechanism(s) drive persistent lithospheric weakening in evolving magma-poor rifts remain largely unknown. In my talk, I will present a series of new results on the East African Rift System, arising from the focused efforts of my group and many collaborators, revealing: 1) the role of rheological inheritance in the localization of border faults during the incipient rift phases, 2) the pervasive mechanical necking of the mantle lithosphere as a major driver of deformation in evolving magma-poor and magma-rich rifts, which in concert with crustal thinning, modulates along-strike variability in lithospheric structure during the rift maturation phases, and 3) the influence of ‘blind melts’ on crustal weakening, deformation, and strain release in the stretching phase of magma-poor extension.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.