Paleoclimate change in Ethiopia around the last interglacial derived from annually-resolved stalagmite evidence

Research output: Contribution to journalArticle

Authors

  • Asfawossen Asrat
  • A Baker
  • M Leng
  • John Hellstrom
  • G. Mariethoz
  • D Yu
  • CN Jex
  • J Gunn

Colleges, School and Institutes

External organisations

  • Connected Waters Initiative Research Centre
  • National Centre for Groundwater Research and Training

Abstract

Oxygen and carbon (C) isotope, growth rate and trace element data are reported for a U-Th dated, annually-laminated stalagmite, GM1 from Goda Mea Cave, Ethiopia. The stalagmite grew intermittently around the last interglacial. The proxy records are used to develop a conceptual growth model of the stalagmite and to assess its potential for revealing a climate signal in this climatically sensitive northeastern African region during an important period in the evolution of Homo sapiens and dispersal of Anatomically Modern Humans out of Africa. Speleothem deposition is of short-duration occurring at ~129 ka, ~120 ka, in an undated growth phase, and at ~108 ka; probably due to tectonic activity. 18 composition is very stable within growth phases (1 variability < 0.76‰), as are Mg/Ca, Sr/Ca and Ba/Ca, all indicative of well-mixed source-waters. A shift to positive 18 values and increased variability in Mg/Ca, Sr/Ca and Ba/Ca prior to growth hiatuses is observed, indicating a loss of the well-mixed water source prior to growth cessation. Mean 18 composition (–3.82 to –7.77‰) is lower than published modern and Holocene stalagmites from the region. Geochemical data, statistical analyses, and a conceptual model of stalagmite growth, demonstrate that climatic conditions recorded by GM1 were wetter than the Holocene. The ~129 ka growth phase particularly presents an annual record of the relative Intertropical Convergence Zone (ITCZ) position. The GM1 record, the oldest high-resolution continental climate record from Ethiopia so far published, presents evidence that any early human migrations which occurred during MIS 5 are likely to have occurred during a wet event in northeast Africa.

Details

Original languageEnglish
JournalQuaternary Science Reviews
Early online date5 Oct 2018
Publication statusPublished - 15 Dec 2018