Comparison of nickel and vanadyl porphyrin distributions of sediments

The distributions of nickel and vanadyl porphyrins of Toarcian shale, northern Germany, and the Monterey Formation, California, were examined. The compositions of nickel and vanadyl porphyrin fractions of extracts from the same sample show substantial differences. The nickel porphyrin distribution i...

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Published inGeochimica et cosmochimica acta Vol. 57; no. 6; pp. 1367 - 1377
Main Authors Sundararaman, Padmanabhan, Boreham, Christopher J.
Format Journal Article
LanguageEnglish
Published United States Elsevier Ltd 01.03.1993
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Summary:The distributions of nickel and vanadyl porphyrins of Toarcian shale, northern Germany, and the Monterey Formation, California, were examined. The compositions of nickel and vanadyl porphyrin fractions of extracts from the same sample show substantial differences. The nickel porphyrin distribution is more complex than the vanadyl porphyrin distribution. While the vanadyl porphyrin distributions of samples from a core are the same, their nickel porphyrin compositions show wide variations. The nickel porphyrins are enriched in “etio” and 3-nor C 30DPEP structures. The vanadyl porphyrins are enriched in the C 33DiDPEP structure. Methylpropano porphyrins are found only in the vanadyl porphyrin fraction, whereas the cycloheptano structural type is predominant in the nickel fraction. C 31DPEP and C 32DPEP are found both in the nickel and vanadyl fractions. Their relative abundance in the two fractions is proportional to the Ni VO porphyrin ratio. The observed differences in the compositions of nickel and vanadyl porphyrin fractions are due to differences in the rate constants for their formation from the pheopigments.
ISSN:0016-7037
1872-9533
DOI:10.1016/0016-7037(93)90078-B