Fast rift propagation at a slow-spreading ridge

Bathymetric, magnetic, gravity, and morphologic data from the flank of the slow-spreading Mid-Atlantic Ridge reveal obliquely oriented features that offset magnetic isochrons and morphological patterns within individual ridge segments. These features form angles of ∼10°–40° with the isochrons and are inferred to result from rift propagation at rates several times the spreading rate, representing the fastest propagators yet observed at a slow-spreading ridge. These fast propagators appear to have formed as a result of tectonic extension migrating along ridge segments as the segments change from more magmatic to less magmatic periods of spreading.