Changing atmospheric Δ^(14)C and the record of deep water paleoventilation ages

• Published in: Paleoceanography
• Main Authors: Adkins, Jess F., Boyle, Edward A.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 1997
• Subjects: Pacific; Shackleton; Ice Sheet; Planktonic foraminifera
• Online Access: https://doi.org/10.1029/97PA00379

We propose a new calculation method to better estimate the deep water ventilation age from benthic-planktonic foraminifera ^(14)C ages. Our study is motivated by the fact that changes in atmospheric Δ^(14)C through time can cause contemporary benthic and planktonic foraminifera to have different initial Δ^(14)C values. This effect can cause spurious ventilation age changes to be interpreted from the geologic data. Using a new calculation method, ^(14)C projection ages, we recalculate the data from the Pacific Ocean. Contrary to previous results, we find that the Pacific intermediate and deep waters were about 600 years older than today at the last glacial maximum. In addition, there are possible signals of ventilation age change prior to ice sheet melting and at the Younger Dryas. However, the data are still too sparse to constrain these ventilation transients. © 1997 American Geophysical Union. Received 19 September 1996; accepted 26 January 1997; published 1 June 1997. We would like to thank Delia Oppo, Nick Shackleton and Daniel Sigman for helpful discussions. Edouard Bard, J. R. Toggweiler and M. L. Delaney provided constructive reviews of the manuscript. J. F. A. was supported by a NASA Global Change Fellowship and a grant from the Tokyo Electric and Power Company. We gratefully acknowledge the support of NSF grant# OCE-94-02198 and NOAA grant # NA46GP0282. Published - Adkins_Paleo1997p337.pdf