Our current understanding of continental rifting is largely based on studies of evolved and relict rift systems. Observations from these studies have motivated and constrained numerical models that describe rift evolution from initiation to rupture. However, there are very few field observations that constrain processes occurring at the earliest stages of rifting and the structural controls on these processes. This project involves a project to investigate the question of what happens in the early stages of continental rifting. The East African Rift System (EARS), because of its proximity to the pole of rotation, exhibits a strong gradient in rift evolution along its length. This provides a unique opportunity to investigate the processes that drive rift initiation and control early rift localization.
The PIs will undertake a multidisciplinary investigation of the southwest branch of the EARS, which includes the very early stage Okavango Rift Zone, where classic geomorphic rift features are just beginning to emerge, and the Mweru, Luangwa (Zambia) and Malawi Rifts, where geomorphic features are fully developed but magma (if present) has yet to breach the surface. The PIs will apply a combination of geophysical, geological, geochemical and geodynamic techniques across the southwest branch of the EARS to test the predictions of those hypotheses. Passive seismic data will constrain lithospheric-scale structure and upper-mantle flow patterns. Wide angle seismic profiling, along with gravity data, will constrain variations in crustal and uppermost mantle structure. Magnetotelluric measurements will provide system-scale constraints on lithospheric thin spots and the presence of melt, while remote sensing and field mapping will be used to map surface deformation. Geochemical analysis of hot spring fluids will identify the presence of mantle-derived melts. Geodynamic modeling will synthesize the new geophysical observations and geochemical results to develop the next generation of continental rifting models.
