Structure and stratigraphy of the Turkana rift from seismic reflection data

Thomas J. Dunkelman, Bruce R. Rosendahl, Jeffrey A. Karson

Research output: Contribution to journalArticle

48 Scopus citations

Abstract

A multichannel seismic survey was conducted on Lake Turkana, a rift lake occupying a portion of the Eastern Branch of the East African Rift System. This survey revealed the presence of a significant rift structure beneath the lake, the extent and structural details of which had been previously unknown. The lake is underlain by a series of half-graben basins which alternate in polarity along the axis of the lake, and are linked end to end by zones of structural high. These half-graben often have Quaternary volcanic centers located near their latitudinal midpoints. Half-graben basins beneath Turkana deepen progressively to the north, attaining thicknesses of up to 4 km. A deep seismic reflector has been identified, and is believed to correspond to the top of a thick series of Mio-Pliocene flood volcanics. Overlying reflectors are thought to correspond to fluvial, lacustrine and volcano-clastic sediments that are Plio-Pleistocene to Recent in age. The style of rifting beneath Lake Turkana is similar to that observed beneath Lake Tanganyika, which occupies a portion of the Western Branch of the East African Rift System. The most noticeable differences are the abundant volcanism and smaller half-graben size associated with Lake Turkana. These differences may be attributed to the warmer, thinner lithosphere underlying the Eastern Branch as compared to that underlying the Western Branch.

Original languageEnglish (US)
Pages (from-to)489-510
Number of pages22
JournalJournal of African Earth Sciences
Volume8
Issue number2-4
DOIs
StatePublished - 1989
Externally publishedYes

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes

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