Enhanced Sedimentation along the equator in the western Pacific

Measurements on cores from the Ontong Java Plateau demonstrate that on-equa tor sediment accumulates more Th-230 than is produced in the overlying wate r column. In contrast, cores from 3.8 degrees N accumulate an amount of exc ess Th-230 more nearly equal to that produced in the overlying water column . Taken together with the observation that both the CaCO3 and non-CaCO3 com ponents of the sediment accumulate at approximately twice the rate in on-eq uator than in off-equator cores [Broecker et al., 1999], this requires eith er that the rain of the larger amount of organic matter generated above the equatorial upwelling plume entrains excess clay and Th-230 during its fall to the sea floor or that physical transport processes, either in the upper ocean or near the sea bed, redistribute sediments in such a way that they preferentially accumulate-in a narrow (+/- 1 degrees latitude) equatorial-c entered belt.