EGU22-12266
https://doi.org/10.5194/egusphere-egu22-12266
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

SEismic imaging of the Ivrea ZonE (project SEIZE) reveals the 3D structure of the Ivrea body near Balmuccia, Italy

Britta Wawerzinek1, Trond Ryberg1, Klaus Bauer1, Manfred Stiller1, Christian Haberland1, Alberto Zanetti3, Luca Ziberna4, György Hetényi5, Michael Weber1, and Charlotte M. Krawczyk1,2
Britta Wawerzinek et al.
  • 1GFZ German Research Centre for Geosciences, Potsdam, Germany (britta.wawerzinek@gfz-potsdam.de)
  • 2TU Berlin, Berlin, Germany
  • 3IGG-CNR, Pavia, Italy
  • 4University of Trieste, Trieste, Italy
  • 5University of Lausanne, Lausanne, Switzerland

The Ivrea-Verbano Zone (IVZ) located in the Italian Alps is known as one of most complete archetypes of continental crust–upper mantle section on Earth (e.g. Pistone et al., 2017). Because of its accessibility at the surface it can be used as natural laboratory to improve the understanding of the crust–mantle transition zone. Several geophysical observables indicate the presence of mantle rocks (high density, high seismic velocity) in the shallow sub-surface (~ 1 km), commonly known as the “Bird’s Head” or Ivrea body (Berckhemer, 1968; Diehl et al., 2009; Scarponi et al., 2021). 

The project SEIZE images and characterizes the shallow upper crust at the Balmuccia site (Italy) providing depth, extent and shape of the outcropping Ivrea body as well as its rock properties. Our tomographic study covers the crust down to about 3 km depth, while seismic reflection imaging is possible down to 6 km depth or deeper. With SEIZE we contribute to the comprehensive ICDP Drilling program in the Ivrea-Verbano ZonE (DIVE, www.dive2ivrea.org).

To tackle this task, a controlled source (vibroseis) seismic experiment was carried out in the region around Balmuccia in October 2020. The seismic survey comprised two crossing profiles with a total length of 28 km which ran along (NNE-SSW) and across (W-E) the Balmuccia peridotite. In total, 432 vibro points were acquired with a nominal distance of ~60 m which were recorded using a fix-spread (110 receivers, ~250 m spacing) and a roll-along setup (330 receivers, ~20 m spacing).

To obtain a structural image of the shallow upper crust various seismic techniques are applied: The fix-spread data set is used to recover the velocity structure down to 3 km depth. By using a 3D Markov chain Monte Carlo travel time tomography a shallow, distinct high velocity body is imaged in 3D near Balmuccia, at the proposed drill site. Reflection seismic processing is applied to the roll-along data set. However, the difficult terrain setting (deep mountain valleys) results in complex wave propagation that is challenging for conventional processing methods (e.g. static and dynamic corrections, CDP stacking). Therefore, pre-stack migration techniques are applied enabling the imaging of steeply dipping structures.

How to cite: Wawerzinek, B., Ryberg, T., Bauer, K., Stiller, M., Haberland, C., Zanetti, A., Ziberna, L., Hetényi, G., Weber, M., and Krawczyk, C. M.: SEismic imaging of the Ivrea ZonE (project SEIZE) reveals the 3D structure of the Ivrea body near Balmuccia, Italy, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12266, https://doi.org/10.5194/egusphere-egu22-12266, 2022.