This project will focus on the paleo-topographic evolution of the Ethiopian Plateau, situated in an extensional tectonic regime, using techniques of quantitative river-profile analysis and paleoaltimetry. The plateau is characterized by the 1.6 km deep Gorge of the Nile, a true rival of the Grand Canyon of North America, formed by the extensive incision of the Blue Nile River. This project will test the hypothesis of early-Pliocene abrupt increase of long-term incision rate of the Blue Nile drainage linked to pulsed plateau growth. By collecting preliminary samples of paleosol carbonates sandwiched between dated Neogene basalts, this research will conduct oxygen-isotope based paleoaltimetry to investigate plateau uplift. From the age-elevation curve of the Ethiopian Plateau, timing, phase, and rate of uplift will be constrained. For some preliminary areas and using Shuttle Radar Topography Mission (SRTM) DEM data, this project will also undertake stream-profile analysis, with ground-truthing, to quantify certain stream parameters such as steepness and concavity indices. This research will produce detailed spatial maps of knickpoints and steepness indices across the study area, and compare these maps with lithologic, precipitation (present day), and structural/tectonic maps of the area to specifically tease out tectonic signals of this elevated landscape.
Understanding the uplift history of the Ethiopian Plateau is crucial to unraveling the tectonic and climatic evolution of the region during the last several million years. This region has long been used as a natural laboratory to understand the processes of continental rifting, which is the first stage in the formation of a new ocean basin, and the evolution of hominids (early humans). The geological information that this study will extract will document how the dynamic landscape of East Africa controlled past climatic changes in the region and created a highly-variable (both spatial and temporal) environment that acted as a perfect cradle for hominid evolution. This project will support graduate and undergraduate students and involve them in high-level research about Earth history and human origins.
