Magmatism distribution and modes of seafloor spreading at a Ridge-transform fault system revealed by marine magnetics

The interaction between transform faults and mid-ocean ridges results in complex magmatic distribution, consequently, intricate crustal accretion processes. In this study, we present magnetic survey data collected over the Argo transform fault in the Central Indian Ocean. Magnetic modeling was conducted along two profiles crossing the adjacent spreading center and one profile over the transform fault. The results reveal the absence of a central magnetic anomaly over the spreading center where it intersects with the transform fault indicating reduced magmatic activity. In this case, plate divergence is alternately driven by magmatic and tectonic processes. Isochron alignment on both sides of the transform fault correlates well, indicating an age offset of 7.5 Myr and a consistent half-spreading rate. The profile over the transform fault and associated fracture zones (FZs) shows strong magmatic signals in the FZ areas near the outside corners, suggesting magma intrusion from the juxtaposed ridge. Conversely, most areas along the transform fault exhibit weak magnetic signals, except for a moderate magnetic anomaly over a transform-parallel serpentinite ridge with gabbro intrusions. These findings further demonstrate that transform faults are not simple conservative plate boundaries and shed light on the dynamics of magmatism and seafloor spreading in ridge-transform systems.