Oceanic Transform Faults as Barriers, Bridges, and Boosters: Geometric Controls on Plume Dispersion Along Segmented Mid-Ocean Ridges

Mantle plumes interacting with mid-ocean ridges (MORs) produce prominent geophysical and geochemical anomalies in oceanic lithosphere. However, the role of oceanic transform faults (OTFs), major discontinuities within MOR systems, in modulating along-axis plume dispersion remains poorly understood. Here, we combine a global dataset of 24 plume–ridge–transform systems with 3D geodynamic modeling to investigate the geometric and kinematic controls on plume behavior along segmented ridges.

Based on spatial relationships among plumes, ridge segments, and transforms, we define three end-member interaction modes: (1) on-ridge, (2) off-ridge, and (3) on-transform– fracture zone plumes. Systematic geodynamic models reveals that OTFs may exert one of three primary roles depending on plume location and system geometry: (i) barriers, which impede along-ridge plume dispersion when long transform offsets create lithospheric discontinuities; (ii) bridges, which permit relatively unimpeded dispersion when plumes lie near transform–ridge junctions or beneath fracture zones; and (iii) boosters, where transform-centered or inside-corner plumes enhance plume transport via strike-slip-induced mantle flow acceleration near the transform fault.

We demonstrate that transform offset length, plume–ridge and plume–transform distances, and ridge spreading rate collectively determine the efficacy of plume dispersion along ridge axes. The proposed framework offers a geometric basis for interpreting observed asymmetries in natural plume–ridge systems and highlight the complex, context-dependent nature of transform fault influence. These insights challenge the classical “transform damming” hypothesis and emphasize the necessity of considering 3D mantle flow dynamics in plume–ridge–transform interactions.