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Nitrogen isotope evidence for expanded ocean suboxia in the early Cenozoic

Kast, Emma R. and Stolper, Daniel A. and Auderset, Alexandra and Higgins, John A. and Ren, Haojia and Wang, Xingchen T. and Martínez-García, Alfredo and Haug, Gerald H. and Sigman, Daniel M. (2019) Nitrogen isotope evidence for expanded ocean suboxia in the early Cenozoic. Science, 364 (6438). pp. 386-389. ISSN 0036-8075. https://resolver.caltech.edu/CaltechAUTHORS:20190425-133429105

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Abstract

The million-year variability of the marine nitrogen cycle is poorly understood. Before 57 million years (Ma) ago, the ^(15)N/^(14)N ratio (δ^(15)N) of foraminifera shell-bound organic matter from three sediment cores was high, indicating expanded water column suboxia and denitrification. Between 57 and 50 Ma ago, δ^(15)N declined by 13 to 16 per mil in the North Pacific and by 3 to 8 per mil in the Atlantic. The decline preceded global cooling and appears to have coincided with the early stages of the Asia-India collision. Warm, salty intermediate-depth water forming along the Tethys Sea margins may have caused the expanded suboxia, ending with the collision. From 50 to 35 Ma ago, δ^(15)N was lower than modern values, suggesting widespread sedimentary denitrification on broad continental shelves. Δ^(15)N rose at 35 Ma ago, as ice sheets grew, sea level fell, and continental shelves narrowed.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1126/science.aau5784DOIArticle
https://science.sciencemag.org/content/364/6438/386PublisherArticle
https://science.sciencemag.org/content/364/6438/386/suppl/DC1PublisherSupporting Information
ORCID:
AuthorORCID
Stolper, Daniel A.0000-0003-3299-3177
Wang, Xingchen T.0000-0001-5316-789X
Martínez-García, Alfredo0000-0002-7206-5079
Sigman, Daniel M.0000-0002-7923-1973
Additional Information:© 2019 American Association for the Advancement of Science. Received 6 August 2018; accepted 26 March 2019. We thank S. Oleynik, A. Weigand, B. Hinnenberg, and F. Rubach for laboratory support and expertise, and P. Mateo for advice on foraminifera picking. This research used samples and/or data provided by the Ocean Drilling Program (ODP) and the International Ocean Discovery Program (IODP). The manuscript was improved by comments from three anonymous reviewers This work was supported by U.S. NSF grants OCE-1060947, 0960802, and 1136345 (D.M.S.) and by the Max Planck Society (G.H.H.); E.R.K. received support from the Tuttle Fund of the Department of Geosciences, Princeton University; D.A.S. was supported by the NOAA Climate and Global Change Postdoctoral Fellowship. Author contributions: D.A.S., D.M.S., and J.A.H. conceptualized the study; E.R.K. and D.A.S. carried out the nitrogen isotope measurements; A.A. and A.M.-G. carried out the TEX_(86) measurements; X.T.W. and H.R. provided methodology and training; E.R.K., D.A.S., J.A.H., and D.M.S. performed data analysis; E.R.K. and D.M.S. prepared the manuscript with input from all authors. The authors have no competing interests to declare. Data and materials availability: All data are available in the manuscript or the supplementary materials.
Funders:
Funding AgencyGrant Number
NSFOCE-1060947
NSFOCE-0960802
NSFOCE-1136345
Max Planck SocietyUNSPECIFIED
Princeton UniversityUNSPECIFIED
National Oceanic and Atmospheric Administration (NOAA)UNSPECIFIED
Issue or Number:6438
Record Number:CaltechAUTHORS:20190425-133429105
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190425-133429105
Official Citation:Nitrogen isotope evidence for expanded ocean suboxia in the early Cenozoic. BY EMMA R. KAST, DANIEL A. STOLPER, ALEXANDRA AUDERSET, JOHN A. HIGGINS, HAOJIA REN, XINGCHEN T. WANG, ALFREDO MARTÍNEZ-GARCÍA, GERALD H. HAUG, DANIEL M. SIGMAN. Science 26 Apr 2019: Vol. 364, Issue 6438, pp. 386-389 DOI: 10.1126/science.aau5784
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94978
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:25 Apr 2019 21:02
Last Modified:09 Mar 2020 13:19

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