EGU2020-1092
https://doi.org/10.5194/egusphere-egu2020-1092
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Coral reconstructed Mid-Holocene seasonality in the southwestern Caribbean

Vanessa Skiba1, Ulrich Struck1,2, Lars Reuning3, Dieter Garbe-Schönberg3, Norbert Frank4, Reinhold Leinfelder1, Aaron O'Dea5, and Jens Zinke6,7,8
Vanessa Skiba et al.
  • 1Palaeontology department, Freie Universität Berlin, Berlin, Germany
  • 2Natural History Museum, Berlin, Germany
  • 3Institute of Geosciences, Christian-Albrechts-Universität, Kiel, Germany
  • 4Institute of Environmental Physics, Heidelberg University, Germany
  • 5Smithsonian Tropical Research Institute, Panama
  • 6School of Geography, Geology and the Environment, University of Leicester, UK
  • 7Department of Environment and Agriculture, Curtin University of Technology, Australia
  • 8School of Geography, Archaeology and Environmental Studies, University of Witwatersrand, South Africa

Seasonality is a dominant factor in the Earth’s climate system, but proxy reconstructions on this time scale are sparse. Corals provide an excellent archive to reconstruct environmental conditions on seasonal time scale using geochemical proxies. Here, we use subfossil (~6.2-7.1 ka BP) Siderastrea siderea and Pseudodiploria labyrinthiformis corals from a pristine Mid-Holocene reef, located in Panamá, southwestern Caribbean. Mid-Holocene insolation seasonality in the Northern Hemisphere was stronger than at present. We investigate the resulting changes in SST and hydrological seasonality using coral Sr/Ca, δ18O and δ13C. To evaluate, if the coral heads can be utilised for geochemical analyses, they have been screened for diagenetic alteration (2D-XRD, thin section analysis). Obtained modern coral Sr/Ca-SST based annual cycle corresponds well with in situ measured SST. Fossil coral Sr/Ca-SST based cycles exceed the modern one by up to 50%. Fossil coral δ18O seasonal amplitudes are higher than the modern one by up to 30% and show a reduction in the mean gradient between wet and dry period, attributable to the northward shift of the Intertropical Convergence Zone. Increased SST and δ18O seasonality are consistent with model simulated SSTs (Kiel Climate Model) and model-based calculated pseudocoral δ18O, but the model underestimates the seasonality increase in the Mid-Holocene.

How to cite: Skiba, V., Struck, U., Reuning, L., Garbe-Schönberg, D., Frank, N., Leinfelder, R., O'Dea, A., and Zinke, J.: Coral reconstructed Mid-Holocene seasonality in the southwestern Caribbean, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1092, https://doi.org/10.5194/egusphere-egu2020-1092, 2019