The ODP color digital imaging system: Color logs of quaternary sediments from the Santa Barbara basin, site 893

Abstract

Digital color logs of cores from leg 146, holes 893A and 893B, have been taken from images captured during January 1993, within days after the cores were split and described. The images were captured and color analyses performed on the Ocean Drilling Program (ODP) color digital imaging system, which was assembled from relatively inexpensive, off‐the‐shelf components. The images were used to calculate sedimentation rates by fitting chronological data from hole 893A to void‐corrected depths determined by eliminating all voids mapped from the images as >1 cm in length measured downcore. Color measurements were made at intervals between 0.22 and 1.0 mm in length, and then Commission Internationale de l'Eclairage (CIE) 1931 chromaticity values were computed. Results plotted within CIE chro‐maticity space lie in close proximity to the Munsell 5Y hue plane, confirming that the instrumental color analysis technique has produced results consistent with those of the human observers who described colors visually. Significant periodicities occurring at 12, 17, 31, and 90 years correlate with sunspot activity cycles, suggesting that color variations may reflect global climatic forcing functions. Linear correlation between color data sets from holes 893A and 893B suggests that as much as 1.2 m of material present at or near the top of hole 893B may not have been recovered from hole 893A, and that there is a 70‐cm depth discrepancy in the opposite direction at 51.5 m below seafloor (mbsf). The article recommends that the 1931 CIE chromaticity system be used routinely for describing colors of geological materials because it readily accommodates the mathematical manipulations required for statistical and time‐series analyses and avoids the subjectivity and other weaknesses inherent in the Munsell Color System.