Résumé
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 delta (super 13) C ranging between -27 per mil and -20 per mil (delta (super 13) C average = -24.1 per mil) compared to Ursa Basin sediments that are generally more depleted in (super 13) C (delta (super 13) C average = -25.7 per mil). Bulk delta (super 15) N values across all basins ranged from -2.7 per mil to 8.2 per mil (delta (super 15) N average = 3.7 per mil) 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 (sub bound) average nearly equal 75%), as estimated from total organic carbon/total nitrogen plots, likely lowered the observed C/N values.