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Diatom D18O evidence for the development of the modern halocline system in the subarctic northwest Pacific at the onset of major Northern Hemisphere glaciation

Swann, George E.A.; Maslin, Mark A.; Leng, Melanie J.; Sloane, Hilary J.; Haug, Gerald H.

Authors

George E.A. Swann george.swann@nottingham.ac.uk

Mark A. Maslin

Melanie J. Leng

Hilary J. Sloane

Gerald H. Haug



Abstract

Establishing a time frame for the development of the modern halocline and stratified water column in the subarctic North Pacific has significant paleoclimatic implications. Here we present a d18O(diatom) record consisting of only two species that represents autumn/winter conditions in the region across the onset of major Northern Hemisphere glaciation boundary. At circa 2.73 Ma a decrease in d18O(diatom) of 4.6% occurs, whereas previously published d18O(foram) results show a 2.6% increase. The d18O(diatom) and Uk37 sea surface reconstructions indicate both a significant freshening of 2–4 practical salinity units and an increase in surface temperatures in the summer to early winter period from circa 2.73 Ma onward. In contrast, the concomitant increase in d18O(foram) is likely to be reflective of conditions beneath the mesothermal structure and/or spring
conditions when warmer sea surface temperatures are not present in the region. These results are consistent with the development of the modern halocline system at 2.73 Ma with year-round stratification of the water column and a strengthened seasonal thermocline during the summer to early winter period, resulting in one of the largest summer to winter temperature gradients in the open ocean. The onset of stratification would also have led to a warm pool of surface water from circa 2.73 Ma, which may have provided a potential source of extra moisture needed to supply the growing North American ice sheets at this time.

Journal Article Type Article
Publication Date Jan 1, 2006
Journal Paleoceanography
Print ISSN 0883-8305
Electronic ISSN 1944-9186
Publisher American Geophysical Union
Peer Reviewed Peer Reviewed
Volume 21
Issue PA1009
APA6 Citation Swann, G. E., Maslin, M. A., Leng, M. J., Sloane, H. J., & Haug, G. H. (2006). Diatom D18O evidence for the development of the modern halocline system in the subarctic northwest Pacific at the onset of major Northern Hemisphere glaciation. Paleoceanography, 21(PA1009), doi:10.1029/2005PA001147
DOI https://doi.org/10.1029/2005PA001147
Publisher URL http://dx.doi.org/10.1029/2005PA001147
Copyright Statement Copyright information regarding this work can be found at the following address: http://eprints.nottingh.../end_user_agreement.pdf
Additional Information Copyright: American Geophysical Union.

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://eprints.nottingham.ac.uk/end_user_agreement.pdf





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