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Volume 9, issue 3
Solid Earth, 9, 649-668, 2018
https://doi.org/10.5194/se-9-649-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Solid Earth, 9, 649-668, 2018
https://doi.org/10.5194/se-9-649-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 16 May 2018

Research article | 16 May 2018

Effects of upper mantle heterogeneities on the lithospheric stress field and dynamic topography

Anthony Osei Tutu1,2, Bernhard Steinberger1,3, Stephan V. Sobolev1,2, Irina Rogozhina4,1, and Anton A. Popov5 Anthony Osei Tutu et al.
  • 1GFZ German Research Centre for Geosciences, Potsdam, Germany
  • 2Institute of Earth and Environmental Science, University of Potsdam, Potsdam, Germany
  • 3Centre for Earth Evolution and Dynamics, University of Oslo, Oslo, Norway
  • 4MARUM Centre for Marine Environmental Sciences, University of Bremen, Bremen, Germany
  • 5Institute of Geosciences, Johann Gutenberg University, Mainz, Germany

Abstract. The orientation and tectonic regime of the observed crustal/lithospheric stress field contribute to our knowledge of different deformation processes occurring within the Earth's crust and lithosphere. In this study, we analyze the influence of the thermal and density structure of the upper mantle on the lithospheric stress field and topography. We use a 3-D lithosphere–asthenosphere numerical model with power-law rheology, coupled to a spectral mantle flow code at 300km depth. Our results are validated against the World Stress Map 2016 (WSM2016) and the observation-based residual topography. We derive the upper mantle thermal structure from either a heat flow model combined with a seafloor age model (TM1) or a global S-wave velocity model (TM2). We show that lateral density heterogeneities in the upper 300km have a limited influence on the modeled horizontal stress field as opposed to the resulting dynamic topography that appears more sensitive to such heterogeneities. The modeled stress field directions, using only the mantle heterogeneities below 300km, are not perturbed much when the effects of lithosphere and crust above 300km are added. In contrast, modeled stress magnitudes and dynamic topography are to a greater extent controlled by the upper mantle density structure. After correction for the chemical depletion of continents, the TM2 model leads to a much better fit with the observed residual topography giving a good correlation of 0.51 in continents, but this correction leads to no significant improvement of the fit between the WSM2016 and the resulting lithosphere stresses. In continental regions with abundant heat flow data, TM1 results in relatively small angular misfits. For example, in western Europe the misfit between the modeled and observation-based stress is 18.3°. Our findings emphasize that the relative contributions coming from shallow and deep mantle dynamic forces are quite different for the lithospheric stress field and dynamic topography.

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The Earth's surface is characterized by numerous geological processes, formed throughout the Earth's history to present day. The interior (mantle), on which plates rest, undergoes convection motion, generating stresses in the lithosphere plate and also causing the plate motion. This study shows that shallow density heterogeneities in the upper 300 km have a limited influence on the modeled horizontal stress field as opposed to the resulting topography, giving the importance depth sampling.
The Earth's surface is characterized by numerous geological processes, formed throughout the...
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