Data report: isotope compositions of sedimentary organic carbon and total nitrogen from Brazos-Trinity Basin IV (Sites U1319 and U1320) and Ursa Basin (Sites U1322 and U1324), deepwater Gulf of Mexico

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Chapter contents Abstract Introduction Methods and materials Results Organic carbon, total nitrogen, and C/N ratios Comparison of C/N with organic carbon and total nitrogen isotopic compositions Acknowledgments References Figures F1. TOC, TN, and isotopic composition. F2. TOC and TN regressions. F3. Comparison of C/N to carbon isotopes. F4. Comparison of C/N to nitrogen isotopes. Tables T1. C and N isotopic compositions. T2. Contribution of N. PDF file			Previous \| Next doi:10.2204/iodp.proc.308.208.2008 Data report: isotope compositions of sedimentary organic carbon and total nitrogen from Brazos-Trinity Basin IV (Sites U1319 and U1320) and Ursa Basin (Sites U1322 and U1324), deepwater Gulf of Mexico¹ William P. Gilhooly III,^2, 3 Stephen A. Macko,² and Peter B. Flemings⁴ Abstract Organic carbon and total nitrogen stable isotopes are reported for sediments drilled during Integrated Ocean Drilling Program Expedition 308. Brazos-Trinity Basin IV sediments exhibited a broad range in organic carbon δ¹³C ranging between –27‰ and –20‰ (δ¹³C average = –24.1‰) compared to Ursa Basin sediments that are generally more depleted in ¹³C (δ¹³C average = –25.7‰). Bulk δ¹⁵N values across all basins ranged from –2.7‰ to 8.2‰ (δ¹⁵N average = 3.7‰) and showed no obvious trend. The relative contribution of marine and terrestrial detrital material deposited within these sediments was inferred by comparing isotopic compositions to C/N values. The significant contribution of inorganic nitrogen (N_bound average ≈ 75%), as estimated from total organic carbon/total nitrogen plots, likely lowered the observed C/N values. ¹Gilhooly, W.P., III, Macko, S.A., and Flemings, P.B., 2008. Data report: isotope compositions of sedimentary organic carbon and total nitrogen from Brazos-Trinity Basin IV (Sites U1319 and U1320) and Ursa Basin (Sites U1322 and U1324), deepwater Gulf of Mexico. In Flemings, P.B., Behrmann, J.H., John, C.M., and the Expedition 308 Scientists, Proc. IODP, 308: College Station, TX (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.308.208.2008 ²Department of Environmental Sciences, University of Virginia, Charlottesville VA 22904, USA. ³Current address: Department of Earth Sciences, University of California Riverside, Riverside CA 92521, USA. williamg@ucr.edu ⁴Institute for Geophysics, University of Texas, Austin TX 78758, USA. Initial receipt: 7 March 2008 Acceptance: 21 May 2008 Publication: 3 September 2008 MS 308-208 Top of page \| Previous \| Next