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The Role of Pre-Existing Precambrian Structures in Rift Evolution: The Albertine and Rhino Grabens, Uganda
Tectonophysics
  • Andrew B. Katumwehe
  • Mohamed G. Abdel Salam, Missouri University of Science and Technology
  • Estella A. Atekwana, Missouri University of Science and Technology
Abstract

We integrated Shuttle Radar Topography Mission (SRTM) Digital Elevation Models (DEM), airborne magnetic, radiometric and three-dimensional Full Tensor Gravity Gradiometry (3D-FTG) data to investigate the role of Precambrian structures in the evolution of the largely amagmatic Miocene-Recent aged Albertine and Rhino grabens in Uganda. These grabens represent the northern segment of the Western Branch of the East African Rift System (EARS). The two NE-trending grabens are connected by a right-stepping transfer zone and they extend within the Archean-Paleoproterozoic Northeast Congo block which represents the northeastern extension of the Congo craton. Our results show the following and highlight the importance of pre-existing structures in the evolution of continental rift systems: (1) The NE-extent of the Albertine full-graben is controlled by NE-trending Precambrian fabric and the graben terminates at its northeastern end when it encounters a multiply folded Precambrian basement terrain with poorly-developed NW-trending structural grain. Additionally, the northeastern termination of the Albertine graben coincides with the presence of NW-trending right-stepping high-density bodies within the Precambrian terrain. (2) The transfer zone between the Albertine and Rhino grabens is controlled by NE-trending Precambrian structures which might have facilitated the development of relay ramp faults. (3) Strain localization within the better-developed southeastern border fault of the Rhino half-graben is facilitated by the presence of Precambrian structures better aligned in a NE-direction in the southeastern part of the basin compared to its northwestern part. (4) Further to the northeast, the Rhino graben is segmented and transitions into a narrower ENE-trending half-graben with a better-developed border fault on its northwestern side. This segmentation coincides with the presence of N-trending Precambrian structures. (5) The Rhino graben terminates farther northeast against the NW-trending Precambrian Aswa shear zone; a prominent structure with complex, but generally NW-trending fabric.

Department(s)
Geosciences and Geological and Petroleum Engineering
Sponsor(s)
National Science Foundation (U.S.)
Comments
Funding of EAR 1255233
Keywords and Phrases
  • Geologic Models,
  • Tracking Radar,
  • Amagmatic Rifts,
  • Digital Elevation Model,
  • East African Rift,
  • Existing Structure,
  • Prominent Structures,
  • Rhino And Albertine Grabens,
  • Shuttle Radar Topography Mission,
  • Strain Localizations,
  • Surveying,
  • Craton,
  • Graben,
  • Precambrian,
  • Rift Zone,
  • Shear Zone,
  • Tectonic Evolution,
  • Tectonic Structure,
  • Uganda,
  • East African Rift System,
  • Pre-existing Structures
Geographic Coverage
Uganda
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2015 Elsevier, All rights reserved.
Publication Date
4-1-2015
Publication Date
01 Apr 2015
Disciplines
Citation Information
Andrew B. Katumwehe, Mohamed G. Abdel Salam and Estella A. Atekwana. "The Role of Pre-Existing Precambrian Structures in Rift Evolution: The Albertine and Rhino Grabens, Uganda" Tectonophysics Vol. 646 (2015) p. 117 - 129 ISSN: 0040-1951
Available at: http://works.bepress.com/mohammed-abdelsalam/65/