Seafloor geomagnetic vector anomaly of the intersection of the Mid-Atlantic Ridge and the Kane Transform Fault: Implications for magnetization of theoceanic crust

We investigated the fine-scale magnetic structure of the oceanic crust and upper mantle around the western intersection of the Mid-Atlantic Ridge and the Kane Transform Fault, using the geomagnetic vector field measured at th e seafloor. The strikes of magnetic boundaries were found to reflect of the local tectonics represented by fault strikes and dips. The ridge-transform intersection is characterized by magnetic boundary strikes rotated eastwar d. The strike directions reflect the direction of recent magmatic activity. These indicate that a few traces of faults extending obliquely from the ri dge axis to the transform fault are associated with neovolcanism. Magnetic boundary strikes in the lower part of the transform valley wall and near a linear trace of the transform fault indicate deformation or tilting of the crust associated with transform faulting. It is also indicated that the cru stal block around the median ridge is tilted by uplift, accompanied by inje ction or emplacement and serpentinization of peridotites. The nodal basin c onsists of extrusive basalts in the E-W direction and N-S trending magnetic strikes. Submersible observation of in situ magnetization of oceanic crust shows that extrusive basalts are typically strongly magnetized. The most r ecent neovolcanic ridge has a mean magnetization of 50 A/m. The mean magnet ization of the ridge axis is 20 A/m. The magnetization of the 3 Ma ridge fl ank in the inside corner high is about 10 A/m. The gabbroic layer in the tr ansform valley has a magnetization less than 2 A/m. The serpentinized perid otites in the median ridge have magnetization less than I A/m. This magneti zation records a reversal in polarity, which is important because the serpe ntinized peridotites contribute to the marine geomagnetic anomaly pattern.