EGU22-3611
https://doi.org/10.5194/egusphere-egu22-3611
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Perturbation of the deep-Earth carbon cycle in response to the Cambrian Explosion

Andrea Giuliani1, Russell N. Drysdale2,3, Jon D. Woodhead2, Noah J. Planavsky4, David Phillips2, Janet Hergt2, William L. Griffin5, Senan Oesch1, Hayden Dalton2, and Gareth R. Davies6
Andrea Giuliani et al.
  • 1ETH Zurich, Institute of Geochemistry and Petrology, Department of Earth Sciences, Switzerland (andrea.giuliani@erdw.ethz.ch)
  • 2School of Geography, Earth and Atmospheric Sciences, The University of Melbourne, Australia
  • 3Laboratoire EDYTEM UMR CNRS 5204, Université Savoie Mont Blanc, France
  • 4Department of Geology and Geophysics, Yale University, USA
  • 5Department of Earth and Environmental Sciences, Macquarie University, Australia
  • 6Department of Earth Sciences, Faculty of Science, Vrije Universiteit Amsterdam, The Netherlands

Earth’s carbon cycle is strongly influenced by subduction of sedimentary material into the mantle. The composition of the sedimentary subduction flux has changed considerably over Earth’s history, but the impact of these changes on the mantle carbon cycle is unclear. Here we show that the carbon isotopes of kimberlite magmas record a fundamental change in their deep-mantle source compositions during the Phanerozoic Eon. The 13C/12C of kimberlites prior to ~250 Myr preserves typical mantle values, whereas younger kimberlites exhibit lower and more variable ratios – a switch coincident with a recognised surge in kimberlite magmatism. We attribute these changes to increased deep subduction of organic carbon with low 13C/12C following the Cambrian Explosion when organic carbon deposition in marine sediments increased significantly. These observations demonstrate that biogeochemical processes at Earth’s surface have a profound influence on the deep mantle, revealing an integral link between the deep and shallow carbon cycles.

How to cite: Giuliani, A., Drysdale, R. N., Woodhead, J. D., Planavsky, N. J., Phillips, D., Hergt, J., Griffin, W. L., Oesch, S., Dalton, H., and Davies, G. R.: Perturbation of the deep-Earth carbon cycle in response to the Cambrian Explosion, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3611, https://doi.org/10.5194/egusphere-egu22-3611, 2022.