TY - JOUR
T1 - Cooling and drying in northeast Africa across the Pliocene
AU - Liddy, Hannah M.
AU - Feakins, Sarah J.
AU - Tierney, Jessica E.
N1 - Funding Information:
This research used samples provided by the Integrated Ocean Discovery Program. Funding for this research was provided by the IODP Schlanger Ocean Drilling Fellowship 2013–2014 to HL; the University of Southern California Women in Science and Engineering program to SF for compound specific isotope analyses and the US National Science Foundation ( OCE-1203892 ) to JT for TEX 86 analyses. We thank Raymonde Bonnefille, Kevin Uno, Tim White, Naomi Levin, Rich Pancost, Tim Herbert, Tim Cronin and Peter Molnar for discussions of aspects of this work. We would like to thank Miguel Rincon and USC undergraduates Alexa Sieracki, Jeff Zhang, Susan Oh, Jack Seeley, Vincent Nguyen, Tiffany Kao, Kyle McAhlaney, Jacob Leonard, Megan McDonald, and Clara Hua for laboratory assistance. This manuscript was improved with the comments of two anonymous reviewers. Data from this publication are archived at the US National Oceanic and Atmospheric Administration and are publically available at: https://www.ncdc.noaa.gov/paleo/study/20145 .
Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2016/9/1
Y1 - 2016/9/1
N2 - Terrestrial records suggest that Northeast Africa experienced drying during the Pliocene; however, these records are often incomplete in time and space, and questions about this shift in climate remain. Here, we use marine sediments from Deep Sea Drilling Project (DSDP) Site 231 in the Gulf of Aden to generate a multi-proxy organic geochemical record of northeast African climate spanning 5.3–2 Ma. This new record provides a regional perspective on climate and serves as context for the fossil record of early hominin evolution. We measured leaf wax carbon (δ13Cwax) and hydrogen (δDwax) isotopic composition and TEX86 (tetraether index of 86 carbons) to investigate past changes in vegetation, aridity, and ocean temperature, respectively. In the earliest Pliocene, we infer warm subsurface ocean temperatures from TEX86, semi-arid conditions on land and extensive C4 grasslands based on δDwax, δ13Cwax and previously published pollen. After 5 Ma, ocean temperatures gradually cooled, and at 4.3 Ma there was a transition to arid conditions on land based on δDwax and pollen. Grasslands yielded to a mid Pliocene landscape of dry shrublands. This drying appears to be an atmospheric response to cooling ocean temperatures, which may reflect changes in tropical ocean circulation, the intensification of Indian Monsoon winds or perhaps other changes associated with Pliocene cooling.
AB - Terrestrial records suggest that Northeast Africa experienced drying during the Pliocene; however, these records are often incomplete in time and space, and questions about this shift in climate remain. Here, we use marine sediments from Deep Sea Drilling Project (DSDP) Site 231 in the Gulf of Aden to generate a multi-proxy organic geochemical record of northeast African climate spanning 5.3–2 Ma. This new record provides a regional perspective on climate and serves as context for the fossil record of early hominin evolution. We measured leaf wax carbon (δ13Cwax) and hydrogen (δDwax) isotopic composition and TEX86 (tetraether index of 86 carbons) to investigate past changes in vegetation, aridity, and ocean temperature, respectively. In the earliest Pliocene, we infer warm subsurface ocean temperatures from TEX86, semi-arid conditions on land and extensive C4 grasslands based on δDwax, δ13Cwax and previously published pollen. After 5 Ma, ocean temperatures gradually cooled, and at 4.3 Ma there was a transition to arid conditions on land based on δDwax and pollen. Grasslands yielded to a mid Pliocene landscape of dry shrublands. This drying appears to be an atmospheric response to cooling ocean temperatures, which may reflect changes in tropical ocean circulation, the intensification of Indian Monsoon winds or perhaps other changes associated with Pliocene cooling.
KW - Africa
KW - Gulf of Aden
KW - Pliocene
KW - TEX
KW - leaf wax
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U2 - 10.1016/j.epsl.2016.05.005
DO - 10.1016/j.epsl.2016.05.005
M3 - Article
AN - SCOPUS:84977156746
SN - 0012-821X
VL - 449
SP - 430
EP - 438
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
ER -