Absorbance band depth at 660 nm (RABD660) data derived from shipboard visible light reflectance spectroscopy, IODP Site 363-U1483

Reflectance spectroscopy of the archive section halves of sediment cores was measured during IODP Expedition 363 using an Ocean Optics USB4000 spectrophotometer on the Section Half Multisensory Logger. Measurements were taken at 2.5 cm spacing and reflectance values for visible wavelengths were recorded in 2 nm wide spectral bins between 380 and 900 nm. We use these in-situ visible light reflectance spectroscopy data to analyse the abundance of diagenetic photosynthesis pigments (chlorins) in bulk sediments along the composite sediment splice from Holes U1483A, U1483B and U1483C. The ratio of pigment fraction expressed in the relative absorption at the 660 nm spectral band is related to chlorin concentration. The relative absorption band depth at 660 nm was calculated using the algorithm: RABD660= {[(6*R590+7*R730)/13]/R660}/Rmean where RABD660 is the relative absorption band depth at 660 nm, R590, R660 and R730 the reflectance at 590, 660 and 730 nm wavelength and Rmean the mean reflectance over the interval 590 to 730 nm (Rein and Sirocko, 2002)