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Twenty-one core samples from DSDP/IPOD Leg 63 were analyzed for products of chlorophyll diagenesis. In addition to the tetrapyrrole pigments, perylene and carotenoid pigments were isolated and identified. The 16 core samples from the San Miguel Gap site (467) and the five from the Baja California borderland location (471) afforded the unique opportunity of examining tetrapyrrole diagenesis in clay-rich marine sediments that are very high in total organic matter. The chelation reaction, whereby free-base porphyrins give rise to metalloporphyrins (viz., nickel), is well documented within the downhole sequence of sediments from the San Miguel Gap (Site 467). Recognition of unique arrays of highly dealkylated copper and nickel ETIO-porphyrins, exhibiting nearly identical carbonnumber homologies (viz., C-23 to C-30; mode = C-26), enabled subtraction of this component (thought to be derived from an allochthonous source) and thus permitted description of the actual in situ diagenesis of autochthonous chlorophyll derivatives. Pigment-yield data, as a function of organic carbon, coupled with the unique arrays of copper and nickel ETIO-porphyrins, have further substantiated the likelihood of a pre-oxidized terrestrial source (cf., Palmer and Baker, 1978) for these pigments. Sediments from the Baja California borderland (Site 471) yielded nickel porphyrin assemblages that had undergone losses of the keto and carboxylic acid moieties with increased sediment depth. Vanadyl porphyrins were found to be present, in an extractable form, only in deepest sediments from the San Miguel Gap suite (1,035 m sub-bottom depth: Section 467-110-3). Perylene, quite abundant in Leg 63 samples, was investigated in order to ascertain the usefulness of this PAH (polyaromatic hydrocarbon) compound as a source indicator parameter (cf., Aizenshtat, 1973; Simoneit, 1978). A direct correlation between possible terrestrial sources of dealkylated Cu/Ni ETIO-porphyrins (cf., Palmer and Baker, 1978) and perylene (cf., Aizenshtat, 1973)—as indicated by the presence or absence and concentration of the latter—was not found. As a result of these studies, however, a potentially more useful role

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Geochemistry of Tetrapyrrole, Carotenoid, and Perylene Pigments in Sediments from the San Miguel Gap (Site 467) and Baja California Borderland (Site 471), Deep Sea Drilling Project Leg 63