Influence of neotectonics on land surface evolution in the upper part of the Blue Nile Basin (Ethiopia): findings from a DEM

  • Michal Kusák Institute of Rock Structure and Mechanics of the Czech Academy of Sciences, Czech Republic
  • Vít Vilímek Charles University, Faculty of Science, Department of Physical Geography and Geoecology, Czech Republic
  • Jozef Minár Comenius University in Bratislava, Faculty of Natural Sciences, Department of Physical Geography and Geoecology, Slovak Republic
Keywords: landscape evolution; neotectonics; river piracy; lineaments; DEM; Main Ethiopian Rift; Ethiopian Highlands

Abstract

The morphometric analysis of lineaments, valleys and signs of erosion taken from a digital elevation model (DEM) made it possible to not only confirm most of the conclusions of the morphotectonic development of the Blue Nile Basin from the previously published results of structural, petrological, tectonic and geochronological analyses, but also to expand our knowledge by applying several new hypotheses. The relative age of the morpholineaments of particular directions was estimated from the character of topographic profiles. Faults,  lineaments and valleys are predominantly oriented in a direction compatible to the published concepts of the tectonic development of the area. Overall, the most abundant NE-SW and NNE-SSW lines reflect a change of extension from a NW-SE to WNW-ESE direction during the Pliocene, in relation to the creation and development  of the Main Ethiopian Rift (MER). This is confirmed by a more developed character of the valleys and less  pronounced erosion activity of the NE-SW oriented valleys contrary to the deeper narrower NNE-SSW valleys  characterised by downward and headward erosion in the second direction. The most pronounced  morphological manifestations of the E-W extension of the MER and western Afar during the Quaternary are  confined to the borders of the MER. The directions of the Pre-Neogene rift structures to the NW-SE and WNW-ESE are compatible with the oldest elements of the current landscape and with the relict fragments of the valley network on the SE boundary of the upper Blue Nile Basin, which could have been drained across current  shoulders of the MER to the S and E before the Late Miocene.

Published
2019-08-26
How to Cite
Kusák, M., Vilímek, V., & Minár, J. (2019). Influence of neotectonics on land surface evolution in the upper part of the Blue Nile Basin (Ethiopia): findings from a DEM. AUC Geographica. https://doi.org/10.14712/23361980.2019.13
Section
Original Articles