Extraterrestrial He-3 in seafloor sediments: Evidence for correlated 100 kyr periodicity in the accretion rate of interplanetary dust, orbital parameters, and Quaternary climate

We have determined the helium abundance and isotopic composition of seafloo r carbonate sediments from the flanks of the Ontong Java Plateau, western e quatorial Pacific Ocean (ODP Site 806). These results provide a two million year record of the burial flux of extraterrestrial He-3, which we believe is a proxy for the terrestrial accretion rate of interplanetary dust partic les. The He-3 burial flux prior to similar to 700 ka was relatively low, si milar to 0.5 pcc cm(-2) kyr(-1), but from 700 ka to the present, the burial flux gradually increased to a value of similar to 1.0 pcc cm(-2) kyr(-1). 100 kyr periodicity in the He-3 burial flux is apparent over the last 700 k yr and correlates with the oxygen isotope record of global climate, with hi gh He-3 burial fluxes associated with interglacial periods. This periodicit y and phase are consistent with previous He-3 measurements in North Atlanti c sediments. Although 100 kyr periodicity in He-3 burial flux is in agreeme nt with recent predictions of the accretion rate of interplanetary dust bas ed on a model of the orbital evolution of asteroidal debris, the measuremen ts and predictions differ by one half cycle in phase. Nevertheless, our obs ervations suggest the terrestrial accretion rate of interplanetary dust is controlled by orbital eccentricity and/or inclination relative to the solar -system invariable plane. Such control is a necessary but not sufficient co ndition for the hypothesis of Muller and MacDonald (1995) that variations i n extraterrestrial dust accretion modulates terrestrial climate with a 100 kyr period. We also identify several brief (<25 kyr) intervals of strongly enhanced He- 3 burial, possibly related to random and transient fluctuations in the accr etion rate of asteroidal or cometary dust particles. Copyright (C) 1998 Els evier Science Ltd.