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Spatial and Temporal Variability of Tectonic Uplift Rates on the Southeastern Ethiopian Plateau, East African Rift Systems

Spatial and Temporal Variability of Tectonic Uplift Rates on the Southeastern Ethiopian Plateau, East African Rift Systems

Name:
Liang Xue

Department:
Geology

Abstract:
We used Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) to extract geomorphic proxies (normalized steepness, stream length gradient, shape factor, and valley height ratio) for the Southwestern Ethiopian Plateau. We also imaged the Moho beneath the plateau using two-dimensional power radially-average power spectral analysis of World Gravity Model (WGM 2012) satellite gravity data. Our aim is to examine the uplift history of the plateau that might be associated with the uprising of the Afar mantle plume and opening of the East African Rift System. This plateau, which is bounded by the Afar Depression in the north and the Main Ethiopian Rift in the east, exposes Cenozoic volcanic rocks at the top underlain by Mesozoic sedimentary rocks. Studies in the Northwestern Ethiopian Plateau resulted in two contrasting models for explaining the uplift history of the region. Thermogeochronology studies suggest a continuous and steady uplift rate since ~30 Ma possibly driven by the ascending Afar mantle plume. While, the interpretation of incision of drainage systems in the plateau suggests three stage and accelerated uplift. Our work found two areas with high rate of tectonic uplift located around the Mendebo and the Ahmar mountains. These regions show two distinct phases of uplift of the Southeastern Ethiopian Plateau. Also, a chronological framework has been provided to the knickpoint migration and associated Quaternary basalt event by knickpoint celerity model.