Jasper, John P; Gagosian, Robert B (1990): Physical properties and bulk organic geochemical results for sediments from DSDP Hole 96-619 [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.707452,

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Supplement to: Jasper, JP; Gagosian, RB (1990): The sources and deposition of organic matter in the late Quaternary Pigmy Basin, Gulf of Mexico. Geochimica et Cosmochimica Acta, 54(4), 1117-1132, https://doi.org/10.1016/0016-7037(90)90443-O

The concentration and carbon isotopic composition (d13C) of sedimentary organic carbon (C_org), N/C ratios, and terrigenous and marine d13C_org endmembers form a basis from which to address problems of Late Quaternary glacial-interglacial climatic variability in a 208.7 m hydraulic piston core (DSDP 619) from the Pigmy Basin in the northern Gulf of Mexico. While interpretations of sedimentary d13C_org time series records are often not unique, paired analyses of d13C_org and N/C are consistent with the hypothesis that the C_org in the Pigmy Basin is a climatically determined mixture of C3-photosynthetic terrigenous and marine organic matter, confirming the earlier d13C_org model of Sackett (1964). A high resolution (~1.4-2.9 Ka/sample) d13C_org record shows that sedimentary organic carbon in interglacial oxygen isotope (sub)stages 1 and 5a-b are enriched in 13C (average +/-1 sigma values are -24.2+/-1.2‰ and -22.9+/-0.7‰ relative to PDB, respectively) while glacial isotope stage values 2 are relatively depleted (-25.6+/-0.5‰). Concentrations of terrigenous and marine sedimentary organic carbon are calculated for the first time using d13C_org and C_org measurements, and empirically determined terrigenous and marine d13C_org endmembers. The net accumulation rate of terrigenous organic carbon is 4.3+/-2.6 times higher in isotope stages 2-4 than in (sub)stages 1 and 5a-b, recording higher erosion rates of terrigenous organic material in glacial times. The concentration and net accumulation rates of marine and terrigenous C_org suggest that the nutrient-bearing plume of the Mississippi River may have advanced and retreated across the Pigmy Basin as sea level fell and rose in response to glacial-interglacial sea level change.