The East African Rift System (EARS) is the most well-developed and diverse example of continental rifting on Earth. Beginning with the formation of oceanic crust in the Afar Triangle, the EARS generally becomes progressively less mature as it extends to the south. Near Lake Victoria, the EARS bifurcates into two branches – one dominated by magmatic activity, the other by seismic activity. This region offers a natural laboratory to explore the upper mantle characteristics of these two types of rifts. Aubreya’s research has indicated that these surficial characteristic persist at depth. She finds broad regions of low velocities underlying the magmaticaly active branch, compared to small isolated pockets of low velocities associated with small-scale volcanism in the seismically-dominated rift branch.
The bifurcated EARS migrates around the thickened lithosphere of the Archean Tanzania Craton, demonstrating the effects that pre-existing structures can have on modern tectonics. Farther to the south, Aubreya was part of a team who demonstrated the existence of a similar region of thickened lithosphere beneath the Bangwelu Block, and the possible existence of a third nascent rift branch forming around this pre-existing feature.
Numerous questions remain about the fascinating East African Rift System. How does crustal structure change locally within the rifts? What is the nature and location of the southern rift terminations? What is the relationship between the EARS and the African Superplume, one of the two largest features of Earth’s mantle. With the help of Colgate student scholars, Aubreya continues to investigate these questions.
(*indicates student author)
Miller, J.C.* and A. Adams, (2016) Sources of Rifting in the East African Rift System from Rayleigh Wave Tomography, Abstract 160770 T51C-2944 presented at at the 2016 Fall Meeting, AGU, San Francisco, CA, 12-16 Dec.
O’Donnell, J. P., A. Adams, A. A. Nyblade, G. D. Mulibo, and F. Tugume (2013), The uppermost mantle shear wave velocity structure of eastern Africa from Rayleigh wave tomography: constraints of rift evolution, Geophysical Journal International, Vol. 194, iss. 2, 961-978.
Adams, A., Nyblade, A., and D. Weeraratne (2012), Upper mantle shear wave velocity structure beneath the East African Plateau: evidence for a deep, plateau-wide low velocity anomaly, Geophysical Journal International, Vol. 189, 123-142.