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Three North African dust source areas and their geochemical fingerprint

Three North African dust source areas and their geochemical fingerprint
Three North African dust source areas and their geochemical fingerprint
North Africa produces more than half of the world's atmospheric dust load. Once entrained into the atmosphere, this dust poses a human health hazard locally. It also modifies the radiative budget regionally, and supplies nutrients that fuel primary productivity across the North Atlantic Ocean and as far afield as the Amazonian Basin. Dust accumulation in deep sea and lacustrine sediments also provides a means to study changes in palaeoclimate, particularly those associated with rainfall climate change. Systematic analysis of satellite imagery has greatly improved our understanding of the trajectories of long-range North African dust plumes, but our knowledge of the dust-producing source regions and our ability to fingerprint their contribution to these export routes is surprisingly limited. Here we report new radiogenic isotope (Sr and Nd) data for sediment samples from known dust-producing substrates (dried river and lake beds), integrate them with published isotope data and weight them for dust source activation. We define three isotopically distinct preferential dust source areas (PSAs): a Western, a Central and an Eastern North African PSA. More data are needed, particularly from the Western PSA, but our results show a change in PSA dust source composition to more radiogenic Nd- and less radiogenic Sr-isotope values from west to east, in line with the overall decreasing age of the underlying bedrock. Our data reveal extreme isotopic heterogeneity within the Chadian region of the Central PSA, including an extremely distinctive geochemical fingerprint feeding the Bodélé Depression, the most active dust source on Earth. Our new analysis significantly improves the reliability by which windblown dust deposits can be geochemically fingerprinted to their distant source regions.
87Sr/86Sr, Bodélé Depression, North Africa, dust source, radiogenic isotopes, εNd
0012-821X
Jewell, Amy Margaret
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Drake, Nick
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Crocker, Anya
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Bakker, Natalie
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Kunkelova, Terezia
32818c35-f763-4ba3-8640-b9334ad4ae6e
Bristow, Charlie
2ddde010-4d19-47e8-bbfe-98c01201b618
Cooper, Matthew
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Milton, James
9e183221-d0d4-4ddb-aeba-0fdde9d31230
Breeze, Paul
a86faa04-cbf3-4fed-8034-96ea40d5de2e
Wilson, Paul A.
f940a9f0-fa5a-4a64-9061-f0794bfbf7c6
Jewell, Amy Margaret
3de1a5a3-b62c-4069-a06e-b2fedb6456e7
Drake, Nick
825cef91-08e8-4533-afd1-992c1738e828
Crocker, Anya
1215fbdd-ad43-408a-bd79-c54c6847e68c
Bakker, Natalie
401a7720-fe86-444f-9b69-144e36e5b5f6
Kunkelova, Terezia
32818c35-f763-4ba3-8640-b9334ad4ae6e
Bristow, Charlie
2ddde010-4d19-47e8-bbfe-98c01201b618
Cooper, Matthew
54f7bff0-1f8c-4835-8358-71eef8529e7a
Milton, James
9e183221-d0d4-4ddb-aeba-0fdde9d31230
Breeze, Paul
a86faa04-cbf3-4fed-8034-96ea40d5de2e
Wilson, Paul A.
f940a9f0-fa5a-4a64-9061-f0794bfbf7c6

Jewell, Amy Margaret, Drake, Nick, Crocker, Anya, Bakker, Natalie, Kunkelova, Terezia, Bristow, Charlie, Cooper, Matthew, Milton, James, Breeze, Paul and Wilson, Paul A. (2020) Three North African dust source areas and their geochemical fingerprint. Earth and Planetary Science Letters, [116645]. (doi:10.1016/j.epsl.2020.116645).

Record type: Article

Abstract

North Africa produces more than half of the world's atmospheric dust load. Once entrained into the atmosphere, this dust poses a human health hazard locally. It also modifies the radiative budget regionally, and supplies nutrients that fuel primary productivity across the North Atlantic Ocean and as far afield as the Amazonian Basin. Dust accumulation in deep sea and lacustrine sediments also provides a means to study changes in palaeoclimate, particularly those associated with rainfall climate change. Systematic analysis of satellite imagery has greatly improved our understanding of the trajectories of long-range North African dust plumes, but our knowledge of the dust-producing source regions and our ability to fingerprint their contribution to these export routes is surprisingly limited. Here we report new radiogenic isotope (Sr and Nd) data for sediment samples from known dust-producing substrates (dried river and lake beds), integrate them with published isotope data and weight them for dust source activation. We define three isotopically distinct preferential dust source areas (PSAs): a Western, a Central and an Eastern North African PSA. More data are needed, particularly from the Western PSA, but our results show a change in PSA dust source composition to more radiogenic Nd- and less radiogenic Sr-isotope values from west to east, in line with the overall decreasing age of the underlying bedrock. Our data reveal extreme isotopic heterogeneity within the Chadian region of the Central PSA, including an extremely distinctive geochemical fingerprint feeding the Bodélé Depression, the most active dust source on Earth. Our new analysis significantly improves the reliability by which windblown dust deposits can be geochemically fingerprinted to their distant source regions.

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Jewell_etal_2020_ACCEPTED - Accepted Manuscript
Restricted to Repository staff only until 27 October 2021.
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More information

Accepted/In Press date: 17 October 2020
e-pub ahead of print date: 27 October 2020
Keywords: 87Sr/86Sr, Bodélé Depression, North Africa, dust source, radiogenic isotopes, εNd

Identifiers

Local EPrints ID: 444841
URI: http://eprints.soton.ac.uk/id/eprint/444841
ISSN: 0012-821X
PURE UUID: cb92a83b-4a2b-4337-9ce4-402e3d89fbc2
ORCID for Matthew Cooper: ORCID iD orcid.org/0000-0002-2130-2759

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Date deposited: 06 Nov 2020 17:31
Last modified: 18 Feb 2021 16:57

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Contributors

Author: Nick Drake
Author: Anya Crocker
Author: Natalie Bakker
Author: Charlie Bristow
Author: Matthew Cooper ORCID iD
Author: James Milton
Author: Paul Breeze
Author: Paul A. Wilson

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