• journal_title：Geology
• Contributor：Kenneth A. Rasmussen ; Robert I. Haddad ; A. Conrad Neumann
• Publisher：Geological Society of America
• Date：1990-
• Format：text/html
• Language：en
• Identifier：10.1130/0091-7613(1990)018<0790:SIROOC>2.3.CO;2
• journal_abbrev：Geology
• issn：0091-7613
• volume：18
• issue：8
• firstpage：790

The stable-isotope composition (δ¹³C) 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 -27.7‰ within the 7900 B.P. paleosol at the base of the core to -11.1‰ 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 +17‰ shift observed in δ¹³C 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.