Geochronology of the pre-KBS Tuff sequence, Omo Group, Turkana Basin

McDougall, Ian and Brown, Francis H. (2008) Geochronology of the pre-KBS Tuff sequence, Omo Group, Turkana Basin. Journal of the Geological Society, 165 2: 549-562. doi:10.1144/0016-76492006-170

Author McDougall, Ian
Brown, Francis H.
Title Geochronology of the pre-KBS Tuff sequence, Omo Group, Turkana Basin
Journal name Journal of the Geological Society   Check publisher's open access policy
ISSN 0016-7649
Publication date 2008-03
Sub-type Article (original research)
DOI 10.1144/0016-76492006-170
Volume 165
Issue 2
Start page 549
End page 562
Total pages 14
Editor Angharad Hills
Place of publication Bath, United Kingdom
Publisher Geological Society Publishing House
Language eng
Subject 0403 Geology
Formatted abstract
The Omo-Turkana Basin of northern Kenya and southern Ethiopia developed in the northern Kenya Rift about 4.3 Ma ago in the Early Pliocene. Nearly 800 m of sediments, included within the Omo Group, crop out in the basin. Numerous rhyolitic tuffs in the sequence not only have facilitated secure correlations between the formations of the Omo Group but also have provided material for precise 40Ar/39Ar age measurements. Here we report ages on alkali feldspar crystals from pumice clasts within tuffs in the lower part of the Omo Group up to the level of the KBS Tuff, which has previously been dated at 1.87 ± 0.02 Ma. The results from 17 stratigraphic levels encompassing the 2.4 Ma time interval from the base of the group to the KBS Tuff provide a numerical time framework for the geological history of the lower part of the Pliocene sequence. The new ages, which have a precision of the order of 1%, are all consistent with the stratigraphic order, providing confidence that they accurately record the ages of the volcanic eruptions, with deposition of the tuffs and pumices occurring shortly thereafter.
Copyright Geological Society Publishing House.

Keyword Deposition
Rift zone
Sequence stratigraphy
Volcanic eruption
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Earth Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 42 times in Thomson Reuters Web of Science Article | Citations
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Created: Thu, 08 Apr 2010, 12:37:59 EST by June Temby on behalf of Faculty of Science