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Heterogeneous crust and upper mantle across southern Kenya and the relationship to surface deformation as inferred from magnetoteluric imaging.

Meju, Maxwell and Sakkas, V. (2007) Heterogeneous crust and upper mantle across southern Kenya and the relationship to surface deformation as inferred from magnetoteluric imaging. Journal of Geophysical Research: Solid Earth, 112 (B4). B04103. ISSN 2196-9356

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    Abstract

    We have used magnetotelluric data imaging to determine the resistivity structure across southern Kenya and our results suggest the presence of a buckled blocky or segmented lithosphere across the region. Prominent steep conductive zones at the Oloololo (OLO) escarpment and eastern rift margin allow us to subdivide the region into three crustal domains. West of OLO, a bow-shaped conductor underlies a 10 km thick resistive upper crustal unit spatially correlating with an exposed Archaean greenstone belt. Between OLO and the eastern rift margin are found steeply dipping alternating conductive and resistive zones that appear buckled. East of this belt are found prominent, 5 to 20 km deep, subhorizontal conductors atop steep resistive blocks with flanking conductors. The main steep features in the crust appear to extend below the seismic Moho and thus suggest the presence of anomalously thick crust across the region. A 50 km-wide and 4–8 km deep w-shaped (double half-graben) structure is suggested at the position of the Kenyan rift. We show that our inferred lateral zoning is consistent with collocated gravity and seismic measurements. We propose a link between the deep resistivity heterogeneity and surface deformation pattern in the area.

    Item Type: Article
    Journal or Publication Title: Journal of Geophysical Research: Solid Earth
    Additional Information: Copyright (2007) American Geophysical Union. Further reproduction or electronic distribution is not permitted. We show that the crust and upper mantle across the Precambrian collision-mountain belt of southern Kenya consist of steeply dipping blocks contrary to previously held views of near-horizontal layering. We propose that lithospheric heterogeneity controlled the deformation seen at the surface. Original ideas from first author, co-author analysed field data. RAE_import_type : Journal article RAE_uoa_type : Earth Systems and Environmental Sciences
    Uncontrolled Keywords: electrical conductivity ; Precambrian tectonics ; Mozambique orogenic belt.
    Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
    Departments: Faculty of Science and Technology > Lancaster Environment Centre
    ID Code: 2123
    Deposited By: ep_importer
    Deposited On: 08 Apr 2008 09:49
    Refereed?: Yes
    Published?: Published
    Last Modified: 17 Sep 2013 08:17
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/2123

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