INTRATRANSFORM ORIGINS OF MIDOCEAN RIDGE MICROPLATES

We present evidence that the Easter and Juan Fernandez microplates ori ginated by rift propagation from within transform fault zones at locat ions far from ridge-transform intersections. An intratransform spreadi ng center may have served as the focal point for each new propagation. Both events appear coincident with a circum-Pacific plate reorganizat ion dated at 5.6 Ma, which may have been related to a change in Pacifi c absolute plate motion and a counterclockwise rotation of Pacific-Naz ca relative plate motion. This intratransform model may be applicable to the generation of other microplates and may thus serve as a general model for microplate origins.