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Bittner, Lucas; Gil-Romera, Graciela; Grady, Dai; Lamb, Henry F.; Lorenz, Eva; Weiner, Mikaela; Meyer, Hanno; Bromm, Tobias; Glaser, Bruno; Zech, Michael

The Holocene lake-evaporation history of the afro-alpine Lake Garba Guracha in the Bale Mountains, Ethiopia, based on δ18O records of sugar biomarker and diatoms

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  • Media type: E-Article
  • Title: The Holocene lake-evaporation history of the afro-alpine Lake Garba Guracha in the Bale Mountains, Ethiopia, based on δ18O records of sugar biomarker and diatoms
  • Contributor: Bittner, Lucas; Gil-Romera, Graciela; Grady, Dai; Lamb, Henry F.; Lorenz, Eva; Weiner, Mikaela; Meyer, Hanno; Bromm, Tobias; Glaser, Bruno; Zech, Michael
  • imprint: Cambridge University Press (CUP), 2022
  • Published in: Quaternary Research
  • Language: English
  • DOI: 10.1017/qua.2021.26
  • ISSN: 0033-5894; 1096-0287
  • Keywords: General Earth and Planetary Sciences ; Earth-Surface Processes ; Arts and Humanities (miscellaneous)
  • Origination:
  • Footnote:
  • Description: <jats:title>Abstract</jats:title><jats:p>In eastern Africa, there are few long, high-quality records of environmental change at high altitudes, inhibiting a broader understanding of regional climate change. We investigated a Holocene lacustrine sediment archive from Lake Garba Guracha, Bale Mountains, Ethiopia, (3,950 m asl), and reconstructed high-altitude lake evaporation history using δ<jats:sup>18</jats:sup>O records derived from the analysis of compound-specific sugar biomarkers and diatoms. The δ<jats:sup>18</jats:sup>O<jats:sub>diatom</jats:sub> and δ<jats:sup>18</jats:sup>O<jats:sub>fuc</jats:sub> records are clearly correlated and reveal similar ranges (7.9‰ and 7.1‰, respectively). The lowest δ<jats:sup>18</jats:sup>O values occurred between 10–7 cal ka BP and were followed by a continuous shift towards more positive δ<jats:sup>18</jats:sup>O values. Due to the aquatic origin of the sugar biomarker and similar trends of δ<jats:sup>18</jats:sup>O<jats:sub>diatom</jats:sub>, we suggest that our lacustrine δ<jats:sup>18</jats:sup>O<jats:sub>fuc</jats:sub> record reflects δ<jats:sup>18</jats:sup>O<jats:sub>lake water</jats:sub>. Therefore, without completely excluding the influence of the ‘amount-effect’ and the ‘source-effect’, we interpret our record to reflect primarily the precipitation-to-evaporation ratio (P/E). We conclude that precipitation increased at the beginning of the Holocene, leading to an overflowing lake between ca. 10 and ca. 8 cal ka BP, indicated by low δ<jats:sup>18</jats:sup>O<jats:sub>lake water</jats:sub> values, which are interpreted as reduced evaporative enrichment. This is followed by a continuous trend towards drier conditions, indicating at least a seasonally closed lake system.</jats:p>