Stalagmite evidence for Early Holocene multidecadal hydroclimate variability in Ethiopia

Asrat, Asfawossen; Baker, Andy; Duan, Wuhui; Leng, Melanie J.; Boomer, Ian; Akter, Rabeya; Mariethoz, Gregoire; Adler, Lewis; Jex, Catherine N.; Yadeta, Meklit; Wang, Lisheng

Abstract

A multiproxy oxygen and carbon isotope (δ13C and δ18O), growth rate, and trace element stalagmite paleoenvironmental record is presented for the Early Holocene from Ethiopia. The annually laminated stalagmite grew from 10.6 to 10.4 ka and from 9.7 to 9.0 ka with a short hiatus at ~9.25 ka. Statistically significant and coherent spectral frequencies in δ13C and δ18O are observed at 15–25 and 19–23 years, respectively. The observed ~1‰ amplitude variability in stalagmite δ18O is likely forced by nonequilibrium deposition, due to kinetic effects during the progressive degassing of CO2 from the water film during stalagmite formation. These frequencies are similar to the periodicity reported for other Holocene stalagmite records from Ethiopia, suggesting that multidecadal variability in stalagmite δ18O is typical. Several processes can lead to this multidecadal variability and operate in different directions. A hydroclimate forcing is likely the primary control on the extent of the partial evaporation of soil and shallow epikarst water and associated isotopic fractionation. The resulting oxygen isotope composition of percolation water is subsequently modulated by karst hydrology. Further isotopic fractionation is possible in-cave during nonequilibrium stalagmite deposition. Combined with possible recharge biases in drip-water δ18O, these processes can generate multidecadal δ18O variability.

Citation

Asrat, A., Baker, A., Duan, W., Leng, M. J., Boomer, I., Akter, R., Mariethoz, G., Adler, L., Jex, C. N., Yadeta, M., & Wang, L. (2022). Stalagmite evidence for Early Holocene multidecadal hydroclimate variability in Ethiopia. Quaternary Research, 110, 67-81. https://doi.org/10.1017/qua.2022.29

• Journal Article Type: Article
• Acceptance Date: May 20, 2022
• Online Publication Date: Jun 29, 2022
• Publication Date: 2022-11
• Deposit Date: Jul 14, 2022
• Publicly Available Date: Dec 30, 2022
• Journal: Quaternary Research
• Print ISSN: 0033-5894
• Electronic ISSN: 1096-0287
• Publisher: Cambridge University Press
• Peer Reviewed: Peer Reviewed
• Volume: 110
• Pages: 67-81
• DOI: https://doi.org/10.1017/qua.2022.29
• Keywords: General Earth and Planetary Sciences; Earth-Surface Processes; Arts and Humanities (miscellaneous)
• Public URL: https://nottingham-repository.worktribe.com/output/8952854
• Publisher URL: https://www.cambridge.org/core/journals/quaternary-research/article/abs/stalagmite-evidence-for-early-holocene-multidecadal-hydroclimate-variability-in-ethiopia/6130F875B29E64131B1B3B9D4E8F67FC