EGU22-6661
https://doi.org/10.5194/egusphere-egu22-6661
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Ocean break-up and related mountain rise controlled by a continentalcrustal root

Anna Makushkina1, Benoit Tauzin2, Meghan S. Miller1, Hrvoje Tkalčić1, and Hans Thybo3
Anna Makushkina et al.
  • 1Australian National University, Research School of Earth Sciences, Canberra, Australia (anna.makushkina@anu.edu.au)
  • 2Université de Lyon, UCBL, ENS Lyon, CNRS, Laboratoire de Géologie de Lyon, Terre, Planètes, Environnement; Villeurbanne, France.
  • 3Eurasia Institute of Earth Sciences, Istanbul Technical University; Istanbul, Turkey.

Large-scale topography is thought to be mainly controlled by active tectonic processes. Fennoscandia is located far from any active tectonic setting and yet includes a mountain range along its passive North Atlantic margin. Models proposed to explain the origin of these enigmatic mountains are based on glacial isostatic adjustments, delamination, long-term isostatic equilibration, and dynamic support from the mantle, yet no consensus has been reached.

Here we demonstrate that Precambrian lithospheric structure of Fennoscandia controlled both Cenozoic oceanic breakup and recent mountain rise in the North Atlantic region. Fennoscandia formed by amalgamation of Proterozoic and Archean continental blocks; using both S- and P-receiver functions, we discovered that the Fennoscandian lithosphere still retains the original structural heterogeneity and its western margin is composed of three distinct blocks. The southern and northern blocks have relatively thin crust (~40-45 km), while the central block has thick crust (~60 km) that most likely was formed by crustal stacking during the Proterozoic amalgamation. The boundaries of the blocks continue into the oceanic crust as two major structural zones of the North-East Atlantic, suggesting that the Fennoscandian amalgamation structures determined the geometry of the ocean opening. We found no evidence for mountain root support or delamination in the areas of high topography that could be related to the mountain formation. Instead, our results suggest that the geometry of the observed features creates conditions favorable for edge-driven convection at the adjacent narrow margins that provides dynamic support for the mountains in Scandinavia.

How to cite: Makushkina, A., Tauzin, B., Miller, M. S., Tkalčić, H., and Thybo, H.: Ocean break-up and related mountain rise controlled by a continentalcrustal root, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6661, https://doi.org/10.5194/egusphere-egu22-6661, 2022.

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