Color - Reflectance Measurements Obtained from Leg 155 Cores

During ODP Leg 155, color reflectance was routinely measured downhole at all but one site to determine light-reflectance levels in the wavelength band of visible light (400 to 700 nm) of the sediments recovered. Reflectance measurements taken on previous ODP legs have demonstrated that lithologic changes in carbonate-rich (>20%) pelagic and hemipelagic sediments can be characterized using these data (e.g., Mix et al., 1992: ODP Leg 138; Curry, Shackleton, Richter, et al., in press: ODP Leg 154). This chapter briefly summarizes our attempts to apply this method to deep-sea fan sediments, which, in general, are characterized by low carbonate and are predominantly terrigenous siliciclastic material. Problems determining color reflectance of terrigenous sediments typical for the Amazon Fan by using a hand scanner system involve both technique and non-mineral characters of the sediment. The method for measurement of color reflectance is described in the "Explanatory Notes" chapter (this volume), and detailed comparisons between color-reflectance patterns and lithology of sediments at individual sites are given in the "Lithostratigraphy" sections of each site report (this volume).