The raw reflectance record of Site 1075, measured at intervals of 4 cm (2 cm in some parts and modified to void space) displays pronounced periodicity in the red/blue ratio at all three holes cored (Fig. 1). Total reflectance shows somewhat similar cycles, albeit less pronounced (Fig. 2). Reflectance of visible light (thirty-one 10-nm-wide spectral bands from 400 to 700 nm) was measured with a Minolta CM-2002 spectrophotometer on split-core surfaces that were covered with a thin, transparent plastic film (e.g., Schneider et. al, 1995).
Preliminary estimates of the time scale, based on biostratigraphic analysis, immediately suggest a strong component of the 23-k.y. precession cycle in the red/blue ratio (see "Lithostratigraphy" section, "Site 1075" chapter, this volume). Variations in the ratio of the red-to-blue wavelengths are weakly correlated with the concentration of organic carbon, but show little or no covariation with concentrations of calcium carbonate (Fig. 3). Also, no correlation with total sulfur was found. The pronounced cyclicity in the precessional band suggests a strong influence of productivity variation. The connection between precession and productivity is well established for late Quaternary sediments in this area (Schneider et al., 1994, 1997).