Geomorphological and geochemical evidence (230Th anomalies) for cross-equatorial currents in the central Pacific

Limited current meter and other data and physical oceanographic models help to explain these observations. Data from current meters 1° north of the equator show a highly asymmetric mesoscale eddy motion here, aligned with the furrows. Phase relationships between near-bed and upper ocean currents suggest an indirect coupling of upper-ocean eddies with the lower ocean. The bottom Ekman layer is predicted theoretically to thicken towards the equator. The resulting reduced bed shear stress may explain the 230Th deposition and more weakly developed furrows at the equator. Given evidence that equatorial accumulation rates of 230Th and extraterrestrial 3He both fluctuated over the Late Pleistocene, we explore how the ideas presented here could help to explain how the geochemical anomalies relate to physical oceanographic processes.