Secondary Plumes Formation Controlled by Interaction of Thermochemical Mantle Plumes With the Mantle Transition Zone

Abstract The causes and global distribution of intraplate volcanism remain poorly understood, particularly the occurrence of scattered magmatism unrelated to large igneous provinces (LIPs). In this study, high‐resolution numerical simulations are employed to examine the interaction between deep thermochemical mantle plumes and the mantle transition zone (MTZ) to clarify its role in plume ascent and surface magmatism. Results demonstrate that the MTZ exerts a significant control on plume behavior, with some plumes ascending directly while others stall and generate secondary upwellings (“baby plumes”), which may contribute to scattered, localized magmatism. The transition from direct ascent to stagnation of the primary (“parent”) thermochemical plume is influenced by temperature, plume volume, Clapeyron slopes, and compositional heterogeneities. Our results highlight the crucial role of the MTZ in how mantle plumes evolve and drive surface magmatism. This provides new insights into why some deep mantle plumes fail to generate LIPs, instead producing widely scattered volcanism.