--> Abstract: Extensional Geologic History of the Blue Nile Basin, Ethiopia, from Remote Sensing Data and Field Studies, by D. Nahid Sultana and Mohamed G. Abdelsalam; #90039 (2005)

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Extensional Geologic History of the Blue Nile Basin, Ethiopia, from Remote Sensing Data and Field Studies

D. Nahid Sultana and Mohamed G. Abdelsalam
The University of Texas at Dallas, Richardson, TX

The interplay between structures and stratigraphy played a significant role in geological evolution of the Blue Nile Basin, situated in NW Ethiopian Plateau and bounded to the east by Main Ethiopian Rift and Afar Depression. The basin is dominated by Mesozoic non-marine clastics and marine non-clastics overlying Precambrian crystalline rocks and topped by Tertiary-Quaternary volcanic rocks. We integrated field studies, and analysis of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), RADARSAT remote sensing data and Digital elevation models (DEMs) extracted from Shuttle Radar Topography Mission (SRTM) and ASTER to highlight stratigraphic and structural styles of Mesozoic sediments and Tertiary-Quaternary volcanics. We used this approach to map stratigraphic units, and normal faults using nearly horizontal nonconformity surface developed between the ~2000m thick volcanics and the 1200m thick Mesozoic sediments. The evolution of Blue Nile Basin is summarized in eight progressive stages: (1) Pre-rift peneplanation of Precambrian rocks; (2) Post-rift fluvial sedimentation of Triassic-Middle Jurassic Lower Sandstone overlying Precambrian rocks; (3) First marine transgression depositing glauconitic sandy-mudstones during Middle Jurassic; (4) Deepening of the basin, indicated by Middle Jurassic Lower Limestone; and evaporation of the basin, indicated by Gypsum units; (5) Second phase of marine transgression depositing Middle-Late Jurassic Upper Limestone; (6) Final regression followed by the deposition of Late Cretaceous Upper Sandstone in alluvial/fluvial condition; (7) Extrusion of basaltic lava during Middle Oligocene-Early Miocene related to mantle plume activity associated with Main Ethiopian Rift and Afar Depression; and (8) Late volcanic events leading to the emplacement of Quaternary volcanic rocks.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005