The orientation and tectonic regime of the observedcrustal/lithospheric stress field contribute to our knowledge of differentdeformation processes occurring within the Earth's crust and lithosphere. Inthis study, we analyze the influence of the thermal and density structure ofthe upper mantle on the lithospheric stress field and topography. We use a 3-Dlithosphere–asthenosphere numerical model with power-law rheology, coupled toa spectral mantle flow code at 300 km depth. Our results are validatedagainst the World Stress Map 2016 (WSM2016) and the observation-basedresidual topography. We derive the upper mantle thermal structure from eithera heat flow model combined with a seafloor age model (TM1) or a globalS-wave velocity model (TM2). We show that lateral density heterogeneities inthe upper 300 km have a limited influence on the modeled horizontal stressfield as opposed to the resulting dynamic topography that appears moresensitive to such heterogeneities. The modeled stress field directions, usingonly the mantle heterogeneities below 300 km, are not perturbed much when theeffects of lithosphere and crust above 300 km are added. In contrast, modeledstress magnitudes and dynamic topography are to a greater extent controlledby the upper mantle density structure. After correction for the chemicaldepletion of continents, the TM2 model leads to a much better fit with theobserved residual topography giving a good correlation of 0.51 in continents,but this correction leads to no significant improvement of the fit betweenthe WSM2016 and the resulting lithosphere stresses. In continental regionswith abundant heat flow data, TM1 results in relatively small angularmisfits. For example, in western Europe the misfit between the modeled andobservation-based stress is 18.3°. Our findings emphasize that therelative contributions coming from shallow and deep mantle dynamic forces arequite different for the lithospheric stress field and dynamic topography.
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