EGU2020-4732
https://doi.org/10.5194/egusphere-egu2020-4732
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Changes in oxygen concentrations of intermediate water in the eastern tropical north Pacific over the last 140,000 years.

Babette Hoogakker1, Christopher Day2, and Melanie Leng3
Babette Hoogakker et al.
  • 1Heriot-Watt, Institute of Life and Environmental Science, Lyell Centre, Edinburgh, UK.
  • 2Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN, Oxford, UK.
  • 3British Geological Survey, Stable Isotope Facility, Keyworth, Nottingham, NG12 5GG, UK.

Intermediate waters (500 - 2000 m) from the equatorial- to North Pacific are currently hypoxic (oxygen concentrations below 120 µmol/kg), while deeper waters are well oxygenated. For the last ice-age, some proxy records suggested that this trend was reversed, with well-oxygenated Pacific intermediate waters, and lower oxygenated deeper waters associated with an increased deep carbon reservoir. Recent work however suggests that there was an overall expansion of oxygen depleted water in the eastern tropical North Pacific during the last glacial period (Hoogakker et al., 2018). To further assess the natural variability in intermediate water dissolved oxygen concentrations over longer time-scales we extend the bottom water oxygen record of ODP Site 1242 (1360 m depth located in the eastern tropical north Pacific), to 140,000 years, using  the benthic foraminifera carbon isotope gradient approach of Hoogakker et al. (2015).  Our reconstructions suggest that oxygen concentrations varied with an approximate 40 kyr period; with lowest concentration during cool periods of the penultimate glacial, MIS 5b, 4 and 2.

How to cite: Hoogakker, B., Day, C., and Leng, M.: Changes in oxygen concentrations of intermediate water in the eastern tropical north Pacific over the last 140,000 years., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4732, https://doi.org/10.5194/egusphere-egu2020-4732, 2020

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