Initiation of the western branch of the East African Rift coeval with the eastern branch

Roberts, E.M., Stevens, N.J., O'Connor, P.M., Dirks, P.H.G.M., Gottfried, M.D., Clyde, W.C., Armstrong, R.A., Kemp, A.I.S., and Hemming, S. (2012) Initiation of the western branch of the East African Rift coeval with the eastern branch. Nature Geoscience, 5 (4). pp. 289-294.

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View at Publisher Website: http://dx.doi.org/10.1038/NGEO1432
 
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Abstract

The East African Rift System transects the anomalously high-elevation Ethiopian and East African plateaux that together form part of the 6,000-km-long African superswell structure. Rifting putatively developed as a result of mantle plume activity that initiated under eastern Africa. The mantle activity has caused topographic uplift that has been connected to African Cenozoic climate change and faunal evolution. The rift is traditionally interpreted to be composed of two distinct segments: an older, volcanically active eastern branch and a younger, less volcanic western branch. Here, we show that initiation of rifting in the western branch began more than 14 million years earlier than previously thought, contemporaneously with the eastern branch. We use a combination of detrital zircon geochronology, tephro- and magnetostratigraphy, along with analyses of past river flow recorded in sedimentary rocks from the Rukwa Rift Basin, Tanzania, to constrain the timing of rifting, magmatism and drainage development in this part of the western branch. We find that rift-related volcanism and lake development had begun by about 25 million years ago. These events were preceded by pediment development and a fluvial drainage reversal that we suggest records the onset of topographic uplift caused by the African superswell. We conclude that uplift of eastern Africa was more widespread and synchronous than previously recognized.

Item ID: 22289
Item Type: Article (Refereed Research - C1)
ISSN: 1752-0894
Date Deposited: 11 Jul 2012 09:39
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040310 Sedimentology @ 33%
04 EARTH SCIENCES > 0403 Geology > 040311 Stratigraphy (incl Biostratigraphy and Sequence Stratigraphy) @ 34%
04 EARTH SCIENCES > 0403 Geology > 040301 Basin Analysis @ 33%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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