Sedimentary fabrics and variation in lamination style in Peru continental margin upwelling sediments

Abstract

Reveals great variation in composition, spacing, and thickness of laminae. The internal fine-structure of diatom ooze laminae indicates a range of depositional mechanisms from fall out from bloom events to deposition from or reworking by bottom currents. Much of the lamination is a spaced diatom ooze lamination, which is characteristic of sequences having relatively low sedimentation rates and records periodic bloom events. The occurrence of varve-type laminations in sequences older than about 100ky suggests that the Peruvian coastal strip may once have had a regular wet season. -from Author