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Stable-isotope record of organic carbon from an evolving carbonate banktop, Bight of Abaco, Bahamas

Kenneth A. Rasmussen, Robert Irwin Haddad and A. Conrad Neumann
Stable-isotope record of organic carbon from an evolving carbonate banktop, Bight of Abaco, Bahamas
Geology (Boulder) (August 1990) 18 (8): 790-794

Abstract

The stable-isotope composition (delta (super 13) C) of total organic carbon (TOC) was measured as a function of depth throughout a 217-cm-thick sequence of Holocene carbonate sediment within the Bight of Abaco lagoon, Little Bahama Bank. Biofacies and lithofacies analyses indicate progressive banktop submergence and paleoenvironmental response during Holocene sea-level rise. Stable-isotope values shift markedly from -27.7ppm within the 7900 B.P. paleosol at the base of the core to -11.1ppm at the present-day sediment-water interface. An abrupt excursion toward heavy-isotope values records the first establishment of Thalassia seagrass upon open-marine flooding. A multitracer approach, combining biofacies, lithofacies, and stable-isotope analysis of TOC confirms that the dramatic +17ppm shift observed in Delta (super 13) C was a direct result of sea-level rise and associated environmental changes over the banktop; there is little evidence of spurious diagenetic overprint. Stable-isotope analyses of organic carbon may enhance the reconstruction of carbonate sequences by revealing a distinctive geochemical signature of banktop flooding, including the onset of growth of otherwise unpreservable Thalassia seagrass.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 18
Serial Issue: 8
Title: Stable-isotope record of organic carbon from an evolving carbonate banktop, Bight of Abaco, Bahamas
Affiliation: Univ. N.C., Curriculum Mar. Sci., Chapel Hill, NC, United States
Pages: 790-794
Published: 199008
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 49
Accession Number: 1990-050120
Categories: Quaternary geologyOceanography
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch map
N26°00'00" - N26°40'00", W78°10'00" - W77°10'00"
N20°45'00" - N28°00'00", W79°30'00" - W72°00'00"
Secondary Affiliation: NASA, Ames Res. Cent., USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1990
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