EGU25-16578, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-16578
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Serpentinite microstructure at the Atlantis Massif – serpentinization reaction or deformation?
Rebecca Kühn1, Rüdiger Kilian1, Luiz Morales2, Andy Parsons3, Barbara John4, Jeremy Deans5, and the IODP Expedition 399 Science Party*
Rebecca Kühn et al.
  • 1Martin-Luther-Universität Halle, Institut für Geowissenschaften & Geographie, Halle, Germany (rebecca.kuehn@geo.uni-halle.de)
  • 2ETH Zürich, Geological Institute, Structural Geology and Tectonics Group, Zürich, Switzerland
  • 3University of Plymouth, School of Geography, Earth and Environmental Sciences, Plymouth, UK
  • 4University of Wyoming, Department of Geology and Geophysics, Laramie, WY, USA
  • 5University of Southern Mississippi, School of Biological, Environmental, and Earth Sciences, Hattiesburg, MS, USA
  • *A full list of authors appears at the end of the abstract

Oceanic core complexes are a common feature along slow-spreading mid-ocean ridges. Serpentinized mantle rocks are exposed at the seafloor in the footwall to large-scale detachment faults. While it is likely that the exposed and rotated footwall has experienced deformation, it is unclear how internal footwall deformation is accommodated by the ultramafic rocks. One example of such an oceanic core complex is the Atlantis Massif at the Mid-Atlantic ridge (30° N) drilled by International Ocean Discovery Program (IODP) Expedition 399. Site U1601 provides the unique opportunity to understand any deformation recorded in serpentinized mantle rocks over >1.2 km depth.

To better understand the depth distribution of deformation and the associated deformation mechanisms, we combine microstructure and crystallographic preferred orientation (CPO) analysis by means of Scanning Electron Microscopy techniques and synchrotron high energy X-ray diffraction. Results show variable microstructures ranging from zoned mesh cells with no CPO, to foliated samples with a strong CPO of both serpentine and magnetite, to serpentinite samples exhibiting deformation microstructures like kinking and dissolution-precipitation features. The origin of characteristic microstructures and CPOs, whether formed due to serpentinization, deformation, or mutual interaction, will be discussed.

IODP Expedition 399 Science Party:

Andrew M. McCaig, Susan Q. Lang, Peter Blum, Natsue Abe, William J. Brazelton, Rémi Coltat , Jeremy R. Deans, Kristin L. Dickerson, Marguerite Godard, Barbara E. John, Frieder Klein, Rebecca Kuehn, Kuan-Yu Lin, C. Johan Lissenberg, Haiyang Liu, Ethan L. Lopes, Toshio Nozaka, Andrew J. Parsons, Vamdev Pathak, Mark K. Reagan, Jordyn A. Robare, Ivan P. Savov, Esther M. Schwarzenbach, Olivier J. Sissmann, Gordon Southam, Fengping Wang, C. Geoffrey Wheat

How to cite: Kühn, R., Kilian, R., Morales, L., Parsons, A., John, B., and Deans, J. and the IODP Expedition 399 Science Party: Serpentinite microstructure at the Atlantis Massif – serpentinization reaction or deformation?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16578, https://doi.org/10.5194/egusphere-egu25-16578, 2025.