The accumulation of extraterrestrial He-3, a tracer for interplanetary dust particles (IDPs), in sediments from the Ontong Java Plateau (OJP; western equatorial Pacific Ocean) has been shown previously to exhibit a regular cyclicity during the late Pleistocene, with a period of similar to100 ka. Those results have been interpreted to reflect periodic variability in the global accretion of IDPs that, in turn, has been linked to changes in the inclination of Earth's orbit with respect to the invariable plane of the solar system. Here we show that the accumulation in OR sediments of authigenic Th-230, produced by radioactive decay of U-234 in seawater, exhibits a 100-ka cyclicity similar in phase and amplitude to that evident in the He-3 record. We interpret the similar patterns of Th-230 and He-3 accumulation to reflect a common origin within the ocean-climate system. Comparing spatial and temporal patterns of sediment accumulation against regional patterns of biological productivity and against the well-established pattern of CaCO3 dissolution in the deep Pacific Ocean leads to the further conclusion that a common 100-ka cycle in accumulation of biogenic, authigenic and extraterrestrial constituents in OR sediments reflects the influence of climate-related changes in sediment focusing, rather than changes in the rate of production or supply of sedimentary constituents. (C) 2002 Elsevier Science B.V. All rights reserved.
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