Oceanic fault zones reconstructed

Abstract

At undersea structures called oceanic spreading centres, two tectonic plates split apart, and molten rock from volcanic activity solidifies to produce the crust of the sea floor. These spreading centres are separated into individual segments that are tens to hundreds of kilometres long. At the ends of the segments, shearing (side-by-side sliding) of the two plates occurs along plate boundaries known as oceanic transform faults. Since their discovery in the mid-1960s 1, these faults have been considered as sites where plate material is neither created nor destroyed. But on page 402, Grevemeyer et al. 2 report that this description is too simplistic. They show that, in a several-kilometre-wide region called the transform deformation zone, the crust generated at one spreading segment undergoes episodes of thinning and then regrowth as it drifts towards and past the adjacent segment.