MODES OF AXIAL REORGANIZATION ON A SLOW-SPREADING RIDGE - THE STRUCTURAL EVOLUTION OF KOLBEINSEY RIDGE SINCE 10 MA

Recently reprocessed aeromagnetic data reveal the slow-spreading Kolbe insey Ridge underwent a regional axial reorganization at anomaly 3A ti me that signaled a major change in the segmentation behavior of the sp reading center. Prior to anomaly 3A, the axis was a sinuous but essent ially continuous feature. The anomaly 3A event separated the axis into four segments, created wide nontransform offsets, and established axi al strikes more nearly orthogonal to the spreading direction. In the s ucceeding similar to 5.5 m.y., the axis continued to evolve by ridge p ropagation, asymmetric spreading, and lateral ridge migration caused b y either ultrafast propagation or synchronous ridge jumps. These data suggest that the brief perturbation of axial structure at anomaly 3A t ime may have altered the long-term segmentation behavior of the ridge. The mechanism for the ridge's segmentation and the ridge's post-segme ntation behavior indicate styles of axial reorganization that may be s ignificant on slow-spreading centers globally.