Temporal evolution of overlapping spreading centers at 16°20′N on the East Pacific Rise

Abstract

A compilation of Sea Beam data on the right-stepping overlapping spreading center (OSC) at 16°20′N on the East Pacific Rise (EPR) and in the surrounding region is presented. Sea Beam data from the rise flanks at 16°20′N reveal three deep basins, at least one of which is flanked by a curved ridge whose morphology is similar to that at the offset. The widths of these offaxis basins range from 8 to 13 km and allow an estimate to be made of the sizes of the offsets at which they were formed. It is proposed that they represent traces on the rise flank which provide a record of the development of the offset and a basis for prediction of its future evolution. The repeated pattern of abandoned overlap basins and cuspate ridges supports the notion that OSCs are episodic on a time scale of approximately 200,000 years and are cyclic in nature. It also reveals an alternation of dominance between the southern and northern segments, which have shifted the location of the discontinuity along the axis so as to create zig-zag traces of basins on the ridge flanks.