Assuming a constant rate of quartz accumulation for deep-sea sediment core Y69-106P, from the Panama Basin, I have estimated the age of samples from the core and have constructed a curve for sedimentation-rate versus time. Stratigraphic controls for the calculated time scale include three C14 measurements, the extinction of the radiolarian Stylatractus universus, correlation with oxygen-isotope curves from other dated cores, and an Ar40/Ar39 age determination.
The model sedimentation rates, when combined with data on mineralogic composition, allow the determination of accumulation rates for CaCO3, opaline SiO2, and remaining “detritus.” Fluctuations in CaCO3 accumulation rates over time correlate with variations in oxygen-isotope ratios in biogenous carbonate from two other equatorial Pacific cores; high oxygen-isotope ratios correlate with high CaCO3 accumulation rates. Opaline SiO2 accumulation rates reflect changes in the dominance of different radiolarian fossil groups, changes which can be related to surface circulation in the Panama Basin.
Spectral analysis of the accumulation rate of CaCO3 in core Y69-106P and of the oxygen-isotope record of core V28-238 indicates a 23,000-yr periodicity. Spectral analysis of the opal accumulation rate suggests a 100,000-yr periodicity, which is an important frequency in the oxygen-isotope record. Both these periodicities are close to those found in fluctuations in the Earth’s orbital parameters. The eccentricity of the orbit fluctuates with an average period of 98,000 yr, and the precession of the equinoxes changes with a period of 22,000 yr.