Quaternary diatoms and palaeoenvironments of the Koora Plain, southern Kenya rift

V. Muiruri, R.B. Owen, Richard Potts, A.L. Deino, A.K. Behrensmeyer, S. Riedl, Nathan Rabideaux, E.J. Beverly, R.W. Renaut, J.W. Moerman, D. Deocampo, J. Tyler Faith, A. Noren, A.S. Cohen, K.B. Shannon, R. Dommain

Research output: Contribution to journalArticlepeer-review

Abstract

The Koora Basin (south Kenya Rift) preserves a continental, tropical, one-million-year record of environmental change driven by global climate, regional tectonism and volcanism. Diatom-based reconstructions from Olorgesailie Drilling Project (ODP) cores indicate lakes that expanded and contracted with conductivities ranging between ∼200 and > 25,000 μS.cm−1 and pH of 7.9–11.2. Benthic and planktonic diatoms document mostly shallow fresh water between 1 Ma and 870 ka with deeper freshwater lakes from 870 to 470 ka. After the Mid-Brunhes Event at about 430 ka, diatoms record many transgression-regression cycles with both freshwater and saline-alkaline lakes present. Palaeosols also indicate episodes of desiccation and lower water tables. Carbonates and zeolites are present in younger sediments, especially after 400 ka. Many high-lake-level stages correlate with low values in ocean benthic δ18O stack data. Most, but not all, low lake levels occurred during higher δ18O MIS intervals, suggesting tectonic and/or volcanic events, in addition to climatic forcing, influenced the drainage, outlet heights and accommodation space. The 870–470 ka period of deeper freshwater lakes at Koora correlates well with the neighbouring Lake Magadi pollen record that suggests generally wetter conditions at this time. Wet-dry cycles after 470 ka at Koora developed when the Magadi record indicates a change towards drier conditions, but with many wetter intervals. High lake level periods at Koora also correlate with phases of diatom-inferred flooding at Magadi. Outcrops north of Koora also document several large lakes during deposition of parts of the Olorgesailie Formation prior to ∼500 ka. The Koora environmental history helps to fill an environmental gap (500–320 ka) encompassing critical changes in hominin lithic technology caused by a hiatus at Olorgesailie. During the first part of this interval (470–390 ka), Koora was occupied by a shallow alkaline lake, suggesting relatively dry conditions. The second part (390–320 ka) was characterised by fluctuating deeper lakes that imply greater variability and wetter conditions. Subsequently, both the Olorgesailie and Koora records indicate variable environments. © 2021 Elsevier Ltd
Original languageEnglish (US)
Article number107106
Number of pages21
JournalQuaternary Science Reviews
Volume267
DOIs
StatePublished - 2021

Bibliographical note

Funding Information:
This research was supported by the National Museums of Kenya, the Oldonyo Nyokie Group Ranch, and the Olorgesailie field team led by J.M. Nume and J.N. Mativo, Research and drilling permits were provided by the Kenyan National Council for Science and Technology, the Kenyan Ministry of Mines, and the National Environmental Management Authority of Kenya. DOSECC Exploration Services supervised drilling by Drilling and Prospecting International (DPI). The LacCore and CSDCO facilities (University of Minnesota) assisted with core handling, processing and storage. Funding was provided by the Peter Buck Fund for Human Origins Research (Smithsonian), the William H. Donner Foundation (R.P.), the Ruth and Vernon Taylor Foundation (R.P.), Whitney and Betty MacMillan (R.P.), National Science Foundation grants EAR 1322017 (A.L.D.) and EAR 1349599 (D.D.), a Smithsonian Postdoctoral Fellowship and the Geo. X - Research Network for Geosciences in Berlin and Potsdam (R.D.), the Swiss National Science Foundation grant P300P2 158501 (M.S.), and the Smithsonian's Human Origins Program (R.P). The Hong Kong Research Grants Council provided funding for diatom studies of the core material.

Funding Information:
This research was supported by the National Museums of Kenya , the Oldonyo Nyokie Group Ranch , and the Olorgesailie field team led by J.M. Nume and J.N. Mativo, Research and drilling permits were provided by the Kenyan National Council for Science and Technology , the Kenyan Ministry of Mines , and the National Environmental Management Authority of Kenya . DOSECC Exploration Services supervised drilling by Drilling and Prospecting International (DPI). The LacCore and CSDCO facilities ( University of Minnesota ) assisted with core handling, processing and storage. Funding was provided by the Peter Buck Fund for Human Origins Research ( Smithsonian ), the William H. Donner Foundation (R.P.), the Ruth and Vernon Taylor Foundation (R.P.), Whitney and Betty MacMillan (R.P.), National Science Foundation grants EAR 1322017 (A.L.D.) and EAR 1349599 (D.D.), a Smithsonian Postdoctoral Fellowship and the Geo. X - Research Network for Geosciences in Berlin and Potsdam (R.D.), the Swiss National Science Foundation grant P300P2 158501 (M.S.), and the Smithsonian's Human Origins Program (R.P). The Hong Kong Research Grants Council provided funding for diatom studies of the core material.

Publisher Copyright:
© 2021 Elsevier Ltd

Keywords

  • Africa
  • Diatoms
  • Hominins
  • Kenya Rift
  • Lake levels
  • Palaeolimnology
  • Pleistocene

Continental Scientific Drilling Facility tags

  • ODP

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