SIMULTANEOUS PRESENCE OF ORBITAL INCLINATION AND ECCENTRICITY IN PROXY CLIMATE RECORDS FROM OCEAN-DRILLING-PROGRAM-SITE-806

Ocean Drilling Program Site 806 in the western Pacific shows evidence of a remarkably constant average sedinnentation rate, This feature all ows us to analyze ancient climate proxies without the need for ''orbit al tuning,'' a standard procedure in prior work, but one that can lead to biased results, Spectral analysis of stable oxygen isotope ratios at this site, a proxy for global ice volume, shows a single narrow pea k with a period approximate to 100 k.y., a result that supports our mo del which links glacial cycles to variations in the inclination of the Earth's orbit, In contrast, spectral analysis of the coarse component fraction of the sediment (primarily foraminifera) shows a structure c haracteristic of standard Milankovitch theory, with a triplet of peaks with periods near those expected from the Earth's eccentricity: 95, 1 25, and 400 k.y. Bispectral analysis confirms these linkages but sugge sts that orbital inclination also plays some role in the coarse fracti on. From the clear presence of both signals in different proxies at th e same site, we conclude that although eccentricity affected the local climate, it is orbital inclination that drove the variations in the g lobal ice volume for the past million years.