EGU21-5529, updated on 04 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Basaltic mantle reservoirs from seismic inversion of reflection data 

Benoit Tauzin1, Lauren Waszek2, Jun Yan3, Maxim Ballmer4, Nick Schmerr5, Juan Carlos Afonso6, and Thomas Bodin1
Benoit Tauzin et al.
  • 1Université de Lyon, France (
  • 2James Cook University, Australia
  • 3ETH Zurich, Switzerland
  • 4University College London, England
  • 5University of Maryland, U.S.
  • 6Macquarie University, Australia

Convective stirring of chemical heterogeneities introduced through oceanic plate subduction results in the marble cake model of mantle composition. A convenient description invokes a chemically unequilibrated mixture of oceanic basaltic crust and harzburgitic lithosphere. Such a composition is required to explain joint observations of shear and compressional waves reflected underneath transition zone (TZ) discontinuities1. The formation of basaltic reservoirs at TZ depth results from complex interaction between phase-change induced chemical segregation, subducted slab downward entrainment, and plume upward advection. However, the dominant mechanism to create and maintain the reservoirs is debated, because both present-day reservoir location and the amount of basalt in these reservoirs are unconstrained. Here, Bayesian inversion of SS- and PP-precursors reflection data indicates that the TZ comprises a global average basalt fraction f = 0.32 ± 0.11. We find the most enriched basaltic reservoirs (f = 0.5-0.6) are associated with recent subduction in the circum-Pacific region. We investigate the efficiency of plate subduction to maintain such reservoirs using global-scale thermochemical  convection models2.

[1] Waszek, L., Tauzin, B., Schmerr, N.C., Ballmer, M., & Afonso, J.C. (in review). A poorly mixed mantle and its thermal state inferred from seismic waves.

[2] Yan, J., Ballmer, M. D., & Tackley, P. J. (2020). The evolution and distribution of recycled oceanic crust in the Earth's mantle: Insight from geodynamic models. Earth and Planetary Science Letters, 537, 116171.

How to cite: Tauzin, B., Waszek, L., Yan, J., Ballmer, M., Schmerr, N., Afonso, J. C., and Bodin, T.: Basaltic mantle reservoirs from seismic inversion of reflection data , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5529,, 2021.