Effects of Composite Rheology on Plate-Like Behavior in Global-Scale Mantle Convection Arnould, Maëlis Rolf, Tobias Cabeza Córdoba, Antonio Manjón Earth's upper mantle rheology controls lithosphere-asthenosphere coupling and thus surface tectonics. Rock deformation experiments and seismic anisotropy measurements indicate that composite rheology (co-existing diffusion and dislocation creep) occurs in the Earth's uppermost mantle, potentially affecting convection and surface tectonics. Here, we investigate how the spatio-temporal distribution of dislocation creep in an otherwise diffusion-creep-controlled mantle impacts the planform of convection and the planetary tectonic regime as a function of the lithospheric yield strength in numerical models of mantle convection self-generating plate-like tectonics. The low upper-mantle viscosities caused by zones of substantial dislocation creep produce contrasting effects on surface dynamics. For strong lithosphere (yield strength > 35 MPa), the large lithosphere-asthenosphere viscosity contrasts promote stagnant-lid convection. In contrast, the increase of upper mantle convective vigor enhances plate mobility for lithospheric strength <35 MPa. For the here-used model assumptions, composite rheology does not facilitate the onset of plate-like behavior at large lithospheric strength. 2023-10-16T09:26:08Z 2023-10-16T09:26:08Z 2023-08-12 journal article Arnould, M., Rolf, T., & Manjón-Cabeza Córdoba, A. (2023). Effects of composite rheology on plate-like behavior in global-scale mantle convection. Geophysical Research Letters, 50, e2023GL104146. [https://doi. org/10.1029/2023GL104146] https://hdl.handle.net/10481/85018 10.1029/2023GL104146 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Wiley