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An isotopic study of biogeochemical relationships between carbonates and organic carbon in the Greenhorn FormationCarbon-isotopic compositions of total carbonate, inoceramid carbonate, micritic carbonate, secondary cements, total organic carbon, and geoporphyrins have been measured in 76 different beds within a 17-m interval of a core through the Greenhorn Formation, an interbedded limestone and calcareous shale unit of Cretaceous age from the Western Interior Seaway of North America. Results are considered in terms of variations in the processes of primary production and in secondary processes. It is shown that the porphyrin isotopic record reflects primary isotopic variations more closely than the TOC isotopic record and that, in these sediments, TOC is enriched in C-13 relative to its primary precursor by 0.6 to 2.8 percent. This enrichment is attributed to isotope effects within the consumer foodweb and is associated with respiratory heterotrophy. Variation in this secondary enrichment are correlated with variations in the isotopic composition of marine carbonate.
Document ID
19900030428
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Hayes, J. M.
(Indiana Univ. Bloomington, IN, United States)
Popp, Brian N.
(Indiana Univ. Bloomington, IN, United States)
Takigiku, Ray
(Indiana Univ. Bloomington, IN, United States)
Johnson, Marcus W.
(Indiana University Bloomington, United States)
Date Acquired
August 14, 2013
Publication Date
November 1, 1989
Publication Information
Publication: Geochimica et Cosmochimica Acta
Volume: 53
ISSN: 0016-7037
Subject Category
Life Sciences (General)
Accession Number
90A17483
Funding Number(s)
CONTRACT_GRANT: NSF PCM-84-04996
CONTRACT_GRANT: NGR-15-003-118
Distribution Limits
Public
Copyright
Other

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