Magnetic Signature of Oceanic Transform Faults and Their Fracture Zones

Abstract Oceanic transform faults (TFs) offset mid‐ocean ridges, juxtaposing different‐aged crust and causing fracture zones (FZ) crossing ocean basins. Mounting evidence challenges the consensus that TFs are conservative plate boundaries, instead supporting the existence of extensional tectonics and two phases of magmatism. These processes should affect the magnetic signature of these systems, yet it is still a matter of debate. Here, we use magnetic data over the Hayes and Oceanographer TFs and six archive data sets to explore the magnetization of TFs on a global scale. Magnetization at ridge‐transform intersections and FZs is stronger than within transform valleys. Weak magnetization in valleys supports tectonic deformation. Strong magnetization, either normal or reversed, traced from the outside corner into FZs, sometimes even overprinting the adjacent older seafloor, documents a second magmatic phase. Both features show a spreading‐rate dependence. Magnetic data comply with other data in supporting that TFs are more dynamic than previously considered.