Tectonics, Mantle Dynamics and Coupled Lithosphere-Mantle-Core Evolution of Earth and Other Rocky Worlds

In recent years, our ability to model the coupled evolution of the tectonics, mantle dynamics and core cooling of Earth and terrestrial planets has improved dramatically, with corresponding improvements in our understanding of these. Simultaneously, the discovery of many rocky exoplanets plus increasingly detailed observations of Earth and solar system planets such as Mars and Venus have given additional motivation to such studies.While planetary tectonics has generally been thought of in terms of the endmembers plate tectonics and stagnant lid (perhaps alternating), we now realise that there is a spectrum of planetary tectonic modes influenced by effective lithospheric strength (~yield stress), intrusive and extrusive magmatism, and other factors. While a simple rheological description of temperature-dependence + plastic yielding can give Earth-like plate tectonics (Tackley, 2000), indicated by reproducing the oceanic plate age-area distribution (Coltice+, 2012) and plate size-frequency distribution (Mallard+, 2016), melting and magmatism facilitate further tectonic modes and greatly influence planetary evolution. While vigorous extrusive magmatism can act as an important “heat pipe” heat transport mechanism (Nakagawa+Tackley, 2012), vigorous intrusive magmatism, which is probably volumetrically larger, can produce a soft, deformable lithosphere resulting in a “plutonic squishy lid” mode (Lourenco+, 2018; 2020) that matches observations of Venus’ lithosphere (Byrne+, 2023; Tian+, 2023). Combinations of these various modes can also exist (Tackley, 2023; Lourenco+Rozel, 2023).Melting and magmatism also have key influences on mantle structure and evolution due to the compositional differentiation that they produce, which tends to result in a build-up of recycled basaltic crust above the core-mantle boundary (influencing core heat flow and evolution (Nakagawa+Tackley, 2014) and at the base of the transition zone (Yan+, 2020), creating partial layering between upper and lower mantles. Indeed, the latter “basalt barrier” effect is found to be much stronger than layering induced by the negative Clapeyron slope of the ringwoodite to bridgmanite+ferropericlase transition.Further important influences include impacts, which may strongly influence early Earth/planetary tectonics (Borgeat+Tackley, 2022) and Mars crustal dichotomy (Cheng+, 2024), grain-size evolution, which strongly influences viscosity and may produce feedback as well as “surprising” behaviour (Shierjott +, 2020; Paul+, 2024) and differential heating due to tidal locking (Meier+, 2021).In this talk, the application of these concepts and mechanisms to the evolution of Earth, Venus, Mars and exoplanets will be discussed.Borgeat, X & PJ Tackley (2022) https://doi.org/10.1186/s40645-022-00497-0 Byrne, P etal. (2021) doi:10.1073/pnas.2025919118 Cheng, KW etal. (2024) https://doi.org/10.1016/j.icarus.2024.116137. Coltice, N etal.  (2012) doi:10.1126/science.1219120. Lourenço, DL etal  (2018) doi:10.1038/s41561-018-0094-8 Lourenço, DL. etal (2020) doi:10.1029/2019GC008756 Lourenço, DL, & AB Rozel  (2023) pp181-196. https://doi.org/10.1016/B978-0-323-85733-8.00006-8 Mallard, CN etal  (2016) doi:10.1038/nature17992. Meier, TG etal (2021) https://doi.org/10.3847/2041-8213/abe400 Nakagawa, T & PJ Tackley (2012) doi:10.1016/j.epsl.2012.02.011. Nakagawa, T & PJ Tackley (2014) doi:10.1002/2013GC005128. Paul, J etal (2024) https://doi.org/10.1186/s40645-024-00658-3 Schierjott, JC etal (2020) https://doi.org/10.5194/se-11-959-2020 Tackley, PJ (2000) https://doi.org/10.1029/2000GC000036 Tackley, PJ (2023) pp159-180. https://doi.org/10.1016/B978-0-323-85733-8.00006-8 Tian, J etal. (2023) https://doi.org/10.1016/j.icarus.2023.115539 Yan, J etal. (2020) https://doi.org/10.1016/j.epsl.2020.116171