Hydroclimate variability in central North Africa during the Plio-Pleistocene

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doi: 10.1130/abs/2016NE-272239
Author(s): Castañeda, Isla S.; Keisling, Benjamin Andrew; Salacup, Jeffrey M.
Author Affiliation(s): Primary:
University of Massachusetts at Amherst, Department of Geosciences, Amherst, MA, United States
Volume Title: Geological Society of America, Northeastern Section, 51st annual meeting
Source: Abstracts with Programs - Geological Society of America, 48(2); Geological Society of America, Northeastern Section, 51st annual meeting, Albany, NY, March 21-23, 2016. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: Central North Africa underwent major hydroclimate fluctuations in the past, most recently during the early Holocene. The Plio-Pleistocene climate of the African continent is of much interest because hominin speciation, extinction and migration events have been linked to changes in global or regional climate. However, long and continuous records of North African climate are relatively rare. Here, we investigate the hydroclimate of central North Africa during the Plio-Pleistocene by examining concentrations of plant leaf waxes and their deuterium isotopic composition (δD) at ODP site 660 (10°N), located offshore Guinea in the tropical Eastern Atlantic. We find that concentrations of leaf waxes are low in the older portion of the record but increase dramatically at ca. 2.5 Ma, reflecting the intensification of the trade winds, in agreement with other studies. Leaf wax δD values at ODP 660 fluctuate by over ca. 70 ppm, attesting to dramatic fluctuations between wet and arid conditions in central North Africa from 4.0 and 0.5 Ma, the interval examined in this study. Interestingly, the most depleted values of the entire record occur at ca. 3.3-3.2 Ma, coinciding with Marine Isotope Stage M2 (∼ 3.3 Ma), indicating wet conditions. The M2 event is recognized globally as a cooling event, which interrupted an otherwise relatively warm Pliocene. Prior to 2.5 Ma, our δD records suggest several major fluctuations between wet and arid conditions within the Pliocene. From ca. 2.5-1.7 Ma, a progressive enrichment in δD occurs, reflecting an overall trend to increasing aridity. Subsequently, a gradual depletion in δD occurs until 0.4 Ma, indicating a progressive return to wetter conditions. Our new hydroclimate records reveal that dynamic hydroclimate shifts in central North Africa, which are believed to have influenced hominin and faunal migration patterns, characterize the past 4.0 Ma, with especially variable conditions noted during the Pliocene.
Year of Publication: 2016
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Africa; Atlantic Ocean; Cenozoic; D/H; Hydrogen; Isotope ratios; Isotopes; Leaves; Leg 108; Neogene; North Africa; North Atlantic; ODP Site 660; Ocean Drilling Program; Organic compounds; Paleoclimatology; Plantae; Pleistocene; Pliocene; Quaternary; Stable isotopes; Tertiary; Waxes
Coordinates: N100048 N100049 W0191444 W0191445
Record ID: 2016092409
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