CONCLUSIONS

1. Shipboard measurements were used to determine the lithologic control on the color data in low-carbonate environments. Preliminary results suggest that the r/b ratio is controlled by the amount of organic carbon in the sediment and that organic matter and biosiliceous sedimentation influence total reflectance. Further measurements of the terrigeneous component and the biogenic component, such as opal contents, are necessary to establish the threshold value for carbonate control on the total reflectance.
2. Spectral analysis of the color data of undisturbed intervals indicates that cycles have orbital scale periods regardless of depth or age. In the Congo Basin, variations in the r/b ratio may reflect productivity changes.
3. Carbonate contents in sediments from the Walvis and Cape Basins strongly influence the total reflectance data. High-reflectance values are especially observed between 0.55 and 0.26 m.y. and may be caused by enhanced carbonate accumulation.