Collaborative Research: Structure and Quaternary Kinematics of Amagmatic Rifting in the Central Afar Triple Junction

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The Afar region in East Africa encompasses the only on-land exposure of a rift-rift-rift triple junction and, hence, affords an unusual opportunity to study the extensional tectonism from the early break-up of continents to seafloor spreading. Present-day extension across the Afar is accommodated by magmatic, axial rift zones (Red Sea, Gulf of Aden, and the main Ethiopian Rift) and amagmatic extension across the region in between. Although much geological and geophysical research has been conducted in the region, knowledge on how extension is accommodated here remains poorly understood. This study will evaluate competing tectonic models of rift formation in the Afar through a combination of structural and landscape analysis, remote sensing, and geochronology. The resultant understanding of extension across Afar rift will provide insight into the evolution of rift-rift-rift triple junctions and continental rifting, in general. The project will advance desired societal outcomes through participation of underrepresented minorities in STEM, improved STEM education through curricular enhancement at a HBCU institution, development of a diverse, globally competitive STEM workforce through the training of graduate and undergraduate students, and increased partnerships through international collaboration.This study will examine the structure and late Cenozoic tectonism in the Afar region in an effort to decipher the neotectonic framework of an active rift-rift-rift triple junction. The interaction between the Gulf of Aden and Red Sea rifts have led to the development of a large-scale accommodation zone that presently is marked by half grabens and tilted fault blocks in central Afar. Understanding the partitioning of extension across Afar rift will provide insight into the evolution of rift-rift-rift triple junctions and continental rifting, in general. This research project aims to conduct fieldwork and remote-sensing analyses that will provide a basis for estimating the magnitude extension across part of the central Afar accommodation zone, as well as Quaternary kinematics. The Afar Stratoid volcanic rocks (4.0 ? 1.0 Ma) are a regionally extensive lava surface that predates the initiation of grabens in the Afar and, hence, provides a viable datum for estimating the magnitude of extension during the Quaternary. Additionally, comparison of long-term (Quaternary) deformation with more recent kinematics (e.g., from late Pleistocene landforms and available GPS observations) provides an initial means of assessing the evolution of the accommodation zone (e.g., co-axial strain versus progressive strain and rotation). Combining structural and neotectonic analyses, the project will accomplish the following: 1) constrain structural geometries and the viability of a regional datum for restoration; 2) estimate horizontal extension across part of the central Afar, including estimation of the contribution of small faults to regional strain; 3) estimate late Pleistocene rates of faulting for major faults using tectonic landforms; 4) use long-term drainage evolution for spatial and temporal constraints on initiation of amagmatic extension.