At shallow burial depths, accreted sediments at an evolved portion of the accretionary prism do not present a formidably complicated structural pattern with polyphase overprinting deformation events but, instead, preserve early deformation structures and magnetic fabrics that formed at the frontal part of the prism. Magnetic fabric formed near the deformation front was simply rotated about a horizontal axis during frontal accretion. A bedding-oblique foliation in poorly lithified and shallowly buried sediments most likely consists of reoriented detrital and/or diagenetic phyllosilicates. This foliation appears to have developed as a flattening plane associated with shearing deformation and alternates with brecciated zones in a fault zone >100 m thick, displaying the geometric relationship of S-C or P-Y fabrics. The formation of a bedding-oblique foliation is considered to reflect initial strain localization related to faulting at the frontal part of the prism.