Evolution of the Pacific-Antarctic Ridge South of the Udintsev Fracture Zone

Abstract

Because of the proximity of the Euler poles of rotation of the Pacific and Antarctic plates, small variations in plate kinematics are fully recorded in the axial morphology and in the geometry of the Pacific-Antarctic Ridge south of the Udintsev fracture zone. Swath bathymetry and magnetic data show that clockwise rotations of the relative motion between the Pacific and Antarctic plates over the last 6 million years resulted in rift propagation or in the linkage of ridge segments, with transitions from transform faults to giant overlapping spreading centers. This bimodal axial rearrangement has propagated southward for the last 30 to 35 million years, leaving trails on the sea floor along a 1000-kilometer-long V-shaped structure south of the Udintsev fracture zone.