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Plio-Pleistocene sedimentation in West Turkana (Turkana Depression, Kenya, East African Rift System): Paleolake fluctuations, paleolandscapes and controlling factors

Nutz, A. and Schuster, M. and Barboni, D. and Gassier, G. and Van Bocxlaer, B. and Robin, C. and Ragon, T. and Ghienne, J.-F. and Rubino, J.-L. (2020) Plio-Pleistocene sedimentation in West Turkana (Turkana Depression, Kenya, East African Rift System): Paleolake fluctuations, paleolandscapes and controlling factors. Earth-Science Reviews, 211 . Art. No. 103415. ISSN 0012-8252. https://resolver.caltech.edu/CaltechAUTHORS:20210114-143038390

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Abstract

Pliocene and Pleistocene sediments from West Turkana (Kenya, East African Rift System) form emblematic syn-rift successions for understanding the evolution of extensional basin and continental rifting. They also constitute world-renowned fossil-bearing strata from which >500 hominin fossils were discovered over the past decades, with >100 inventoried archeological sites. However, associated sedimentary dynamics and architectures as well as paleoenvironments are only partially reconstructed and the relative contribution of climate and tectonism to paleoenvironmental change over time remains unclear. Here, through the interpretation of sedimentary facies, the delineation of sequences and the analysis of δ¹³C in soil carbonates, we provide the first exhaustive reconstruction from ~4.00 to ~0.75 Ma of (i) fluctuations of the paleolake that occupied the Turkana Depression, (ii) the successive sedimentary dynamics and related paleolandscapes that characterized the West Turkana area and (iii) respective roles of climate and tectonism in the sedimentation. We show evidence for seven major transgression-regression (T-R) cycles between ~4.00 and ~ 0.75 Ma superimposed locally by lower amplitude T-R cycles. Comparing the sedimentological interpretations and the δ¹³C values in soil carbonates (literature data), we reveal that fluctuations of rainfall over the Ethiopian Dome, which hosts the drainage basin of the Omo River — the main tributary of Lake Turkana — controlled high-amplitude lake level fluctuations during the Plio-Pleistocene period. We also demonstrate that vegetation and tree cover evolved differently in the Omo Valley and West Turkana. Furthermore we outline that two different sedimentary systems reflecting two distinct modes of sedimentation alternated through times in the West Turkana area as a response to the variations in sediment supply coming from the western rift shoulder (i.e. Lapurr Range) that alternatively generated wave- or river-dominated sedimentary systems. In conclusion, we reveal that climate regulated water input, paleolake water-level fluctuations and vegetation. Tectonism determined sediment supply to the basin controlled in West Turkana by pulses of increased activity of the main border fault (i.e., the Murua Rith Lapurr Fault).


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.earscirev.2020.103415DOIArticle
Additional Information:© 2020 Elsevier. Received 17 July 2020, Revised 10 October 2020, Accepted 19 October 2020, Available online 24 October 2020. This work is a contribution to the Rift Lake Sedimentology project (RiLakS) funded to MS and AN by the Total Oil Company between 2014 and 2016. This work benefited from the ANR HADOC (Human Ancestors Dispersal: the role of Climate) project; (ANR-17-CE31-0010-02) led by DB and from the 80PRIME CNRS project (EnviroMolSed) led by BVB. We thank the Kenyan guides, Francis Emekwi and Sammy Lokorodi who worked with us in the field. This research project was conducted in partnership with the National Oil Corporation of Kenya. We specifically thank George Muia, Kivuti Nyagah, Sumayya Hassan-Athmani, and Ambrose Ofafa. Permission to conduct geological fieldwork was provided by NACOSTI. We are grateful to Sonia Harmand, Xavier Boës and the “West Turkana Archeological Project” for field facilities and discussions. Finally, we thank the two anonymous reviewers and the editor Ch. Fielding for their very useful comments that definitely improved the manuscript. Authors of the manuscript entitled: “Plio-Pleistocene sedimentation in West Turkana (Turkana Depression, Kenya, East African Rift System): paleolake fluctuations, paleolandscapes and controlling factors” claims that they have NO conflicts of interest to declare.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Total Oil CompanyUNSPECIFIED
Agence Nationale pour la Recherche (ANR)ANR-17-CE31-0010-02
Centre National de la Recherche Scientifique (CNRS)EnviroMolSed
Subject Keywords:Nachukui Fm; Omo Group; Rift basin; Pliocene
Record Number:CaltechAUTHORS:20210114-143038390
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210114-143038390
Official Citation:A. Nutz, M. Schuster, D. Barboni, G. Gassier, B. Van Bocxlaer, C. Robin, T. Ragon, J.-F. Ghienne, J.-L. Rubino, Plio-Pleistocene sedimentation in West Turkana (Turkana Depression, Kenya, East African Rift System): Paleolake fluctuations, paleolandscapes and controlling factors, Earth-Science Reviews, Volume 211, 2020, 103415, ISSN 0012-8252, https://doi.org/10.1016/j.earscirev.2020.103415.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107491
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:14 Jan 2021 23:52
Last Modified:14 Jan 2021 23:52

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