EGU2020-7732
https://doi.org/10.5194/egusphere-egu2020-7732
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Zn isotopes in deep sea corals: a useful palaeoceanographic archive?

Susan Little1,2, Tina van De Flierdt2, David Wilson1, Mark Rehkämper2, Jess Adkins3, and Laura Robinson4
Susan Little et al.
  • 1University College London, Department of Earth Sciences, Gower Place, London, WC1E 6BS, UK
  • 2Imperial College London, Department of Earth Science and Engineering, London, SW7 2BP, UK
  • 3California Institute of Technology, Pasadena, CA91125, USA
  • 4University of Bristol, School of Earth Sciences, Bristol, BS8 1RJ, UK

Zinc (Zn) is an important bioessential trace element. Its distribution in the modern oceans reflects a combination of biological uptake, remineralization and the physical ocean circulation. Furthermore, the partitioning behaviour of Zn (DZn) and its isotopes (δ66Zn) in carbonates has been linked to ambient seawater carbonate chemistry [1-3].

Development of Zn isotopes in carbonates as a palaeoceanographic tool has been hampered by the high concentrations of Zn in contaminating material, such as lithogenic or authigenic (e.g. Fe-Mn oxide) phases. However, deep-sea corals are large enough to be subjected to aggressive physical and chemical cleaning, enabling effective removal of contaminating phases. They also have several other advantages over traditional palaeoclimate archives, including the ability to assign precise absolute ages to individual specimens based on uranium-series dating [4].

Here we present Zn/Ca and δ66Zn data for a suite of modern and recent (<1000 yr) deep sea corals from six ocean regions spanning the far North Atlantic to the Tasman Sea. We observe what appears to be species-specific Zn partitioning behaviour, but no clear links between DZn or coral δ66Zn and ambient seawater carbonate chemistry. Overall, there is good agreement between measured or best-guess modern seawater δ66Zn and coral aragonite δ66Zn values, suggesting that corals of species Desmophyllum dianthus and genus Caryophyllia do not significantly fractionate Zn isotopes during calcification. Deep sea corals may thus provide a useful archive of the past ocean Zn isotope composition and its spatial variability.

[1] Marchitto T. M., Curry W. B. and Oppo D. W. (2000). Paleoceanography 15, 299–306. 
[2] van Dijk, I., de Nooijer, L. J., Wolthers, M., & Reichart, G. J. (2017). Geochimica et Cosmochimica Acta 197, 263-277. 
[3] Mavromatis, V., González, A. G., Dietzel, M., & Schott, J. (2019). Geochimica et Cosmochimica Acta 244, 99-112. 
[4] Robinson, L. F., Adkins, J. F., Frank, N..., & van de Flierdt, T. (2014), DSR Part II 99, 184-198.

 

How to cite: Little, S., van De Flierdt, T., Wilson, D., Rehkämper, M., Adkins, J., and Robinson, L.: Zn isotopes in deep sea corals: a useful palaeoceanographic archive? , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7732, https://doi.org/10.5194/egusphere-egu2020-7732, 2020