TY - JOUR
T1 - Paleoclimate change in Ethiopia around the last interglacial derived from annually-resolved stalagmite evidence
AU - Asrat, Asfawossen
AU - Baker, Andy
AU - Leng, Melanie J.
AU - Hellstrom, John
AU - Mariethoz, Gregoire
AU - Boomer, Ian
AU - Yu, Dorothy
AU - Jex, Catherine N.
AU - Gunn, John
N1 - Funding Information:
Stable isotope analyses were funded by NERC Isotope Geosciences Facility (IP-1099-0509) to AB, AA, CNJ and MJL. Fieldwork to the Mechara caves and subsequent sample preparation (lamina counting, drilling) was supported by START-PACOM grant to AA, a Royal Society grant to AA and AB, and a Leverhulme Trust International Network led by AB. U-Th analyses were supported by a UNSW Early Career Researcher grant to CNJ. The School of Earth Sciences of the Addis Ababa University supported and facilitated fieldwork. AA is grateful to the Wissenschaftskolleg zu Berlin where he has been a fellow during the 2017/2018 Academic Year. We thank Henry Lamb and the late Mohammed Umer, who have been very helpful during the successive field trips to the Mechara caves. We would like to particularly recognize the significant contributions of Henry Lamb and Mohammed Umer to understanding the Holocene and Late Pleistocene climate history of Ethiopia. We are grateful to two anonymous reviewers and the editor for the valuable comments that helped to improve the manuscript. Chinese composite and Soreq Cave stalagmite data were obtained from that archived at the World Data Center for Paleoclimatology:
Funding Information:
Stable isotope analyses were funded by NERC Isotope Geosciences Facility ( IP-1099-0509 ) to AB, AA, CNJ and MJL. Fieldwork to the Mechara caves and subsequent sample preparation (lamina counting, drilling) was supported by START-PACOM grant to AA, a Royal Society grant to AA and AB, and a Leverhulme Trust International Network led by AB. U-Th analyses were supported by a UNSW Early Career Researcher grant to CNJ. The School of Earth Sciences of the Addis Ababa University supported and facilitated fieldwork. AA is grateful to the Wissenschaftskolleg zu Berlin where he has been a fellow during the 2017/2018 Academic Year. We thank Henry Lamb and the late Mohammed Umer, who have been very helpful during the successive field trips to the Mechara caves. We would like to particularly recognize the significant contributions of Henry Lamb and Mohammed Umer to understanding the Holocene and Late Pleistocene climate history of Ethiopia. We are grateful to two anonymous reviewers and the editor for the valuable comments that helped to improve the manuscript. Chinese composite and Soreq Cave stalagmite data were obtained from that archived at the World Data Center for Paleoclimatology:
Publisher Copyright:
© 2018 Elsevier Ltd
PY - 2018/12/15
Y1 - 2018/12/15
N2 - Oxygen and carbon (δ18Ο/δ13C) 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. δ18Ο composition is very stable within growth phases (1σ variability < 0.76‰), as are Mg/Ca, Sr/Ca and Ba/Ca, all indicative of well-mixed source-waters. A shift to positive δ18Ο 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 δ18Ο 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.
AB - Oxygen and carbon (δ18Ο/δ13C) 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. δ18Ο composition is very stable within growth phases (1σ variability < 0.76‰), as are Mg/Ca, Sr/Ca and Ba/Ca, all indicative of well-mixed source-waters. A shift to positive δ18Ο 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 δ18Ο 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.
KW - Last interglacial
KW - Northeast Africa
KW - Oxygen isotopes
KW - Paleoclimate
KW - Speleothem
UR - http://www.scopus.com/inward/record.url?scp=85048585035&partnerID=8YFLogxK
U2 - 10.1016/j.quascirev.2018.06.016
DO - 10.1016/j.quascirev.2018.06.016
M3 - Article
AN - SCOPUS:85048585035
SN - 0277-3791
VL - 202
SP - 197
EP - 210
JO - Quaternary Science Reviews
JF - Quaternary Science Reviews
ER -
