Chlorophyll Derivatives in DSDP Leg 22 Sediments

Intermediate and Late Diagenetic Tetrapyrrole Pigments, Leg 41: Cape Verde Rise and Basin

“…Previously, free base porphyrins have been reported in Pleistocene, Pliocene (Baker et al, in press), Miocene (Baker and Smith, 1975;and Smith and Baker, 1974), and Cretaceous (Baker et al, in press) sediments. In this particular area, however, samples younger than Eocene were devoid of free base porphyrins.…”

“…10) is indicative of the degree of reduction in line with expectations for chlorins isolated from Lower Cretaceous sediments. The UV-visible spectrum is characterized by shorter wavelength red bands (656-659 nm) which can result from increasing reduction of ring conjugating groups, such as the 9-keto and 2-vinyl substitutents (Smith and Baker, 1974).…”

Chlorophyll Derivatives in DSDP Leg 31 Sediments

“…From a study of Recent sediments, it is concluded that dechelation, loss of magnesium, was the first step in chlorophyll diagenesis (Smith and Baker, 1974). A comparison of the data in Table 2 with Leg 15 and Leg 22 results suggests that the pheophytins and pheophorbides formed upon chlorophyll dechelation undergo a smooth and continuous degradation through the Quaternary and into the middle Tertiary by reduction or loss of ring conjugating groups.…”

“…The general procedure described for treatment of Leg 15 (Baker and Smith, 1973) and Leg 22 (Smith and Baker, 1974) cores and the modified procedure used in the analysis of Leg 14,20,26,27, and 29 sediment samples (Baker and Smith, this volume) was followed during the investigation of Leg 31 core samples. The experimental procedure is outlined in Figure 1.…”

“…An understanding of the reactions and mechanisms of the early phases of chlorophyll diagenesis was the goal of the investigation of a suite of Leg 15 Pleistocene cores (Baker and Smith, 1973). Next, attempts were made to unravel and extend the diagenetic scheme into the Tertiary and Upper Cretaceous through a study of Leg 22 and Leg 29 sediment cores (Smith and Baker, 1974;Baker and Smith, in press). However, samples from these legs were very low in tetrapyrrole pigment concentration, and consequently pigment characterization depended entirely upon electronic absorption spectroscopy and chromatographic properties of the compounds.…”