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Gravity tectonics of topographic ridges: halokinesis and gravitational spreading in the western Ogaden, Ethiopia

Mege, D. and Le Deit, L. and Rango, T. and Korme, T. (2013) Gravity tectonics of topographic ridges: halokinesis and gravitational spreading in the western Ogaden, Ethiopia. Geomorphology, 193, pp. 1-13. Elsevier. DOI: 10.1016/j.geomorph.2013.03.018 ISSN 0169-555X

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Abstract

The Cenozoic history of the western Ogaden region of Ethiopia, between the Ethiopian rift and the South Afar margin, is marked by uplift and incision of the Ogaden plateau down to the Gorrahei Formation, an upper Cretaceous evaporite formation. Debuttressing of this and the overlying sedimentary formations resulted in widespread and spectacular gravitational spreading landforms over a minimum surface area of 15,000 km2, most of which remains unstudied. After clearing up some misconceptions about the surface geology of the study area, the Kebenawa Ridge in the Audo Range, observations are reported that point to a tectonic style controlled by halokinesis and subsequently, gravitational spreading. The role of diapirism and karstification in the observed halokinesis is discussed, as well as the influence of halokinesis on gravitational spreading. Spreading is in part akin to sackung, in that ridge deformation features include a crestal graben and basal ridge topography extrusion, and deformation was triggered by lateral ridge debuttressing. Ridge spreading also presents analogy with gravitational spreading of the Canyonlands grabens in the Needles District, Canyonlands National Park, Utah. The scale and the mechanisms are found to be basically similar, but two differences are noted. First, incision by the drainage network in response to plateau uplift in Ethiopia has debuttressed the topography along two parallel rivers, instead of a single river (the Colorado River) in Utah. Secondly, incision proceeded to the base of the evaporite layer in the Ogaden, whereas incision has not exceeded the top of the evaporite layer in Utah. These differences may have influenced the details of the spreading mechanisms in ways that remain to be investigated. Overall, in Ethiopia, association of halokinesis and a transitional mode of gravitational spreading at the interface between narrow ridge spreading (sackung) and plateau spreading (Canyonlands-type), illustrates a fascinating and unusual ridge evolution style.

Item URL in elib:https://elib.dlr.de/81997/
Document Type:Article
Additional Information:Bisher nur online erschienen.
Title:Gravity tectonics of topographic ridges: halokinesis and gravitational spreading in the western Ogaden, Ethiopia
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Mege, D.Laboratoire de Planétologie et Géodynamique UMR 6112, CNRS, Université de Nantes, Nantes, FranceUNSPECIFIED
Le Deit, L.laetitia.ledeit (at) dlr.deUNSPECIFIED
Rango, T.Nicholas School of the Environment, Division of Earth and Ocean Sciences, Duke University, Durham, USAUNSPECIFIED
Korme, T.Regional Centre for Mapping of Resources for Development, Nairobi, KenyaUNSPECIFIED
Date:23 March 2013
Journal or Publication Title:Geomorphology
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:193
DOI :10.1016/j.geomorph.2013.03.018
Page Range:pp. 1-13
Publisher:Elsevier
ISSN:0169-555X
Status:Published
Keywords:Ethiopia Gravitational spreading
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Science and Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Erforschung des Weltraums
DLR - Research theme (Project):R - Vorhaben Exploration des Sonnensystems
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research
Deposited By: Knauer, Andrea
Deposited On:19 Apr 2013 14:03
Last Modified:13 Jan 2014 10:47

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