1. 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.
- Author
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Bittner, Lucas, Gil-Romera, Graciela, Grady, Dai, Lamb, Henry F., Lorenz, Eva, Weiner, Mikaela, Meyer, Hanno, Bromm, Tobias, Glaser, Bruno, and Zech, Michael
- Subjects
HOLOCENE Epoch ,DIATOMS ,LAKES ,BIOMARKERS ,SUGAR analysis ,DOMOIC acid - Abstract
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
18 O records derived from the analysis of compound-specific sugar biomarkers and diatoms. The δ18 Odiatom and δ18 Ofuc records are clearly correlated and reveal similar ranges (7.9‰ and 7.1‰, respectively). The lowest δ18 O values occurred between 10–7 cal ka BP and were followed by a continuous shift towards more positive δ18 O values. Due to the aquatic origin of the sugar biomarker and similar trends of δ18 Odiatom , we suggest that our lacustrine δ18 Ofuc record reflects δ18 Olake water . 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 δ18 Olake water 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. [ABSTRACT FROM AUTHOR]- Published
- 2022
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