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Orbital and Suborbital‐Scale Variations of Productivity and Sea Surface Conditions in the Gulf of Alaska During the Past 54,000 Years: Impact of Iron Fertilization by Icebergs and Meltwater

Romero, Oscar E.; LeVay, Leah J.; McClymont, Erin L.; Müller, Juliane; Cowan, Ellen A.

Orbital and Suborbital‐Scale Variations of Productivity and Sea Surface Conditions in the Gulf of Alaska During the Past 54,000 Years: Impact of Iron Fertilization by Icebergs and Meltwater Thumbnail


Authors

Oscar E. Romero

Leah J. LeVay

Juliane Müller

Ellen A. Cowan



Abstract

As a high-nutrient and low-chlorophyll region, the modern Gulf of Alaska (GoA) is strongly impacted by the limitation of iron. Paleostudies along the Alaskan slope have mainly focused on reconstructing environmental conditions over the past 18 ka. Based on micropaleontological, biogeochemical, and sedimentological parameters, we explore a sediment record covering the past 54 ka at Integrated Ocean Drilling Program Site U1419 to understand the impact of orbital- and suborbital-scale climate variability on productivity and sea-surface conditions. Close to the Cordilleran Ice Sheet (CIS), Site U1419 is ideally located to elucidate how the evolution of a large ice mass and glacial processes affected orbital- and suborbital-scale changes in nutrients (e.g., iron) supply. Meltwater discharge from the northern CIS impacted sea surface dynamics of GoA coastal waters. The corresponding increases in bulk biogenic concentrations during Marine Isotope Stage (MIS) 3 and MIS 2 (54–17 ka) suggests a direct impact from iron fertilization. The lack of a consistent relationship between productivity and SST suggests that cooling of surface waters was not the dominant control on primary producers. The inundation of the subaerially exposed continental shelf during the last deglacial (17–10 ka) warming could have served as a major micronutrient source, accounting for a deglacial peak in production. Low productivity after the last deglaciation suggests reduced iron availability, which we link to reduced meltwater inputs from smaller ice masses onshore. Our multiproxy approach reveals a more comprehensive picture of late Quaternary productivity variations compared to earlier studies along the Alaskan margin. The impact of tidewater glaciers and meltwater discharge on past marine productivity and nutrient budget dynamics of high-latitude coastal regions is discussed.

Citation

Romero, O. E., LeVay, L. J., McClymont, E. L., Müller, J., & Cowan, E. A. (2022). Orbital and Suborbital‐Scale Variations of Productivity and Sea Surface Conditions in the Gulf of Alaska During the Past 54,000 Years: Impact of Iron Fertilization by Icebergs and Meltwater. Paleoceanography and Paleoclimatology, 37(1), Article e2021PA004385. https://doi.org/10.1029/2021pa004385

Journal Article Type Article
Acceptance Date Dec 24, 2021
Online Publication Date Dec 26, 2021
Publication Date Jan 3, 2022
Deposit Date Jan 4, 2022
Publicly Available Date Mar 29, 2024
Journal Paleoceanography and Paleoclimatology
Electronic ISSN 2572-4525
Publisher American Geophysical Union
Peer Reviewed Peer Reviewed
Volume 37
Issue 1
Article Number e2021PA004385
DOI https://doi.org/10.1029/2021pa004385

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Published Journal Article (1.4 Mb)
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Publisher Licence URL
http://creativecommons.org/licenses/by-nc-nd/4.0/

Copyright Statement
© 2021. The Authors.

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.





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