How did plate tectonics evolve? Insights from 3-D spherical thermochemical convection simulations

Plate tectonics is a fundamental framework for understanding the geodynamic processes shaping our planet, including seismicity, volcanism, mountain building, and even the long-term climate system and habitability of our planet. However, how plate tectonics evolved over 4.5 billion years remains a major unanswered question. In this study, we employ dynamically self-consistent three-dimensional thermochemical geodynamic models to simulate plate tectonics evolution with physically realistic parameters. Our results demonstrate that plate tectonics undergoes three main stages due to differing dominant mantle cooling modes. Initially, magmatism dominates surface heat transport, with extrusive volcanism leading to a mobile heat-pipe mode, characterised by a high level of volcanism, large surface heat flux, and highly mobile plates in the first 1.5 billion years. This differs from the "heat-pipe" mode occurring on Jupiter's satellite Io by additionally having plate-like behaviour as well as crustal delamination and lithospheric dripping. As the mantle cools, it transitions to a stable mode where mantle convection patterns and their surface expressions become stable for around 1-2 billion years, followed by a smooth evolution to present-day plate tectonics. Our model matches key observations of the surface heat flux, strain rate, plate velocity, and plate distribution patterns, indicating that the early mobile heat pipe mode plays a crucial role in efficiently extracting heat from the mantle. Magmatic intrusion is also expected to have important effects, which we will examine. This study may provide insights into the Earth's dynamic processes and mantle-atmosphere feedback related to plate tectonics and the dynamic evolution of other terrestrial planets, which ultimately affect the long-term climate system and habitability of our planet.