GALAPAGOS RIFT AT 86-DEGREES-W - MORPHOLOGICAL WAVE FORMS - EVIDENCE FOR A PROPAGATING RIFT

A combination of near-bottom and multibeam surveys of the N-S spreading Galapagos Rift reveals periodic morphological transitions from highs to lows along fault scarps with amplitudes of 90-140 m and wavelengths of 24-30 km. All fault scarps reflect similar wave forms, yet the highs and lows are offset by a consistent phase shift with each successive increment of time. Fault scarp morphology realigns approximately every 0. 33 m. y. This progression along strike, distance, and time infers either postemplacement tectonics resulting from antisymmetric distribution of stresses in young crust, oscillating volcanism, or propagation of a magma chamber(s) along the axis of the spreading center.