Constraining Plio‐Pleistocene Shifts in Northwest African Hydroclimate, Ecosystem Distributions, and Marine Productivity: New Paleo‐Records Across the Mid‐Pleistocene Transition
Name
Paleoceanog and Paleoclimatol - 2024 - O’Mara - Constraining Plio‐Pleistocene Shifts in Northwest African Hydroclimate .pdf
Description
Published version
Size
3.45 MB
Format
Adobe PDF
Checksum (MD5)
ec2044f20fdae176488be109cb2c1639
Author(s)
O’Mara, Nicholas A
Skonieczny, Charlotte
McGee, David
Winckler, Gisela
Bory, Aloys J‐M
Bradtmiller, Louisa I
Malaizé, Bruno
Polissar, Pratigya J
Date Issued
June 22, 2024
Journal
Paleoceanography and Paleoclimatology
Publisher
American Geophysical Union
Citation
O’Mara, N. A., Skonieczny, C., McGee, D., Winckler, G., Bory, A. J.-M., Bradtmiller, L. I., et al. (2024). Constraining Plio-Pleistocene shifts in Northwest African hydroclimate, ecosystem distributions, and marine productivity: New paleo-records across the Mid-Pleistocene Transition. Paleoceanography and Paleoclimatology, 39, e2023PA004777.
Version
Final published version
Abstract
Northwest Africa transitioned from a wet/vegetated landscape toward drier/sparser conditions sometime between the late‐Pliocene and the late‐Pleistocene. However, our understanding of the precise timing and nature of this transition is hampered by a paucity of paleo‐records which bridge these two intervals. Here we report new plant‐wax isotope as well as dust and opal flux records from the relatively brief interval ∼1.1–1.0 million years ago (Ma) to evaluate the astronomical timescale controls of Northwest African hydroclimate and vegetation during the Mid‐Pleistocene Transition (MPT) and, in context with published records, the drivers of long‐term climate and ecological trends over the Plio‐Pleistocene. The tempo and amplitude of the Northwest African monsoon rainfall swings closely track low latitude insolation forcings over the last 5 Ma. However, we demonstrate that a pronounced mean state decline in monsoon strength likely occurred following the MPT most likely instigated by increasing Atlantic meridional sea surface temperature gradients or declines in the strength of the meridional overturning circulation. The northward extent of vegetation does not track changes in monsoon strength over the Plio‐Pleistocene and thus may be more strongly influenced by changes in monsoon rainfall extent or ecosystem disturbances. Progressively diminished dust fluxes following a decline in monsoon strength after 1.0 Ma is consistent with reduced production and subsequent depletion of fine‐grained sediments in the Sahara. Synchroneity between dust and opal fluxes across timescales suggests nutrient delivery to the surface ocean via dust plays a key role in marine primary productivity off the coast of Northwest Africa.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
10.1029/2023pa004777
