Basaltic breccias of the Clipperton fracture zone (east Pacific): sedimentation and tectonics in a fast-slipping oceanic transform

Investigations of the Clipperton transform fault, a fast-slipping (11 cm/yr) transform plate boundary offsetting the East Pacific Rise, indicate that the most common types of rocks occurring in this setting comprise a distinctive suite of sedimentary breccias and mudstones. These rocks occur within a narrow (<5 km wide) domain of rugged terrain inferred to be the surface expression of strike-slip faulting. Active mass wasting and breccia formation occur in young crust as it passes through the transform fault domain. The sediments are the products of physical and chemical disintegration and tectonic abrasion of basaltic crust, initially formed at the ridge-transform intersections. As a result of differential vertical movements of crustal blocks, associated with wrench tectonics, these sediments undergo multiple cycles of erosion and redeposition. These distinctive assemblages may serve as indicators of oceanic crust from transform fault zones exposed in some ophiolites. -from Authors