2D Versus 3D Numerical Simulations of Mantle Plume and Lithosphere Interaction: Quantitative Comparison and Scaling Analysis

Mantle plumes are a key phenomenon in geodynamics, connecting the deep Earth interior with surficial tectonic plates. Numerical simulations are essential for studying plume dynamics and their interactions with overlying lithosphere. While 3D models could better capture the geometric features of plumes, 2D simulations offer superior computational efficiency in large-scale and high-resolution scenarios, particularly when rheologically complex geological processes are involved. Thus, both 2D and 3D models have been widely applied in previous numerical studies. However, due to geometric effects, they may yield different results for the same parameters; we need to know how to build the proper scaling relationship between 2D and 3D models. Here, we systematically compare the 2D versus 3D mantle plume in two different regimes. In the first regime with only a plume head, the 2D plume should have a smaller diameter (65%–100% of the 3D value) and lower temperature (reduced by 0–60 K relative to the 3D case) to best match 3D model result. In the second regime with a continuous plume tail, a much smaller diameter (30%–45%) but counter-intuitively higher temperature (increased by 20–100 K) are needed for the 2D model to best approximate 3D result. Further analytical studies indicate that such discrepancies are mainly controlled by the conservations of area (2D) versus volume (3D) of plume materials. These numerical and analytical results provide quantitative relationships between 2D and 3D plume models, which act as a theoretical reference for interpretation of previous models as well as guidance for future studies.