Structural Control on the Marine Incursion and Flooding History of the Dallol Depression, Northern Afar (Northeast Ethiopia)
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Date
2017-12-04
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Addis Ababa University
Abstract
The present study area is situated in the tectonically active Dallol Depression, northern sector of the Danakil Depression, NE of Ethiopia. The main objective of the present study was to evaluate structural control on the Red Sea incursion and flooding history of the Dallol Depression along with production of geological map of the region. To accomplish the so set objective, fieldwork, remote sensing and seismic investigations (from secondary source) were carried out. Structural analysis, band combination and ratio enhancement techniques and DEM analysis enabled the discrimination of different lithologies and delineation of regional structures. Produced geologic map revealed that the northern Danakil Depression and the western margin may represent the complete sequence of rocks spanning from the Neoproterozoic to the Holocene and the dominant structural trend in the study area is NNW followed by N-S and NE trending structures. The study enabled identification of basement rocks, limestone, sandstone, basalt, gypsum and associated coral reefs, alluvial sediments, conglomerate and salt formation. Kinematic analysis of fault-slip data collected from the field indicate NE-SW extension direction coinciding with the regional extension direction in which oblique-slip sense of movement with dominant dip-slip component is exhibited. Dynamic analysis of conjugate fault sets depict that the tensional stress represented by σ3 is parallel to the overall extension direction across the Red Sea. Observation from DEM and differential GPS measurements showed that the western margin of the Depression has been affected by faulting which lead to the desiccation of the Dallol Depression from the Red Sea in combination sea level drop.
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Keywords
Dallol Depression, Marine Incursion, Remote Sensing, Enhancement, DEM, Seismic