A comparison of lignin and stable carbon isotope compositions in quaternary marine sediments

Hedges, John I.; Geen, Alexander van

doi:10.1016/0304-4203(82)90047-0

Cited by 39 publications

(7 citation statements)

References 22 publications

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“…In core 8AD, from a clam colony, the d 13 C DIC reaches À48% at 12 cm below seafloor. Clearly, such low d 13 C values measured in these stations affected by fluid venting are more negative than the minimum values of À22% for particulate organic carbon in this area [Hedges and Mann, 1979;Hedges and Van Geen, 1982]. Thus the d 13 C DIC data from Hydrate Ridge undoubtedly reflect oxidation of methane within the near-surface sediments, consistent with the very large rates of ambient methane oxidation rates measured in the upper 2 cm of the sediment (Figures 2 and 3).…”

Section: Fluid Flow Regime and Pore Water Datasupporting

confidence: 62%

Is methane venting at the seafloor recorded by δ¹³C of benthic foraminifera shells?

et al. 2003

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[1] The isotopic composition of the dissolved inorganic carbon (DIC) collected at sites of active methane discharge on Hydrate Ridge, Oregon, reveals anaerobic methane oxidation mediated by bacteria, with d 13 C DIC reaching values as low as À48% in the upper 4 cm of the sediment. In spite of the high sulfide levels in the discharging fluids, living specimens of the benthic foraminifera Uvigerina peregrina are abundant in the vents, probably owing to the rich bacterial food source. Although pore water d 13 C DIC is extremely low (À6 to À48%), the d 13 C values of living (Rose Bengal stained) foraminifera shells collected from active methane seeps are not significantly lower than those observed in nonventing pelagic sediments, and are within the range expected from local organic matter decomposition (0 to À4%). The apparent d 13 C disequilibrium between biogenic calcite and DIC suggests that at seep localities, foraminifera calcify mostly during periods when there is little methane discharge or during intermittent episodes of seawater flow into the sediments. The isotopic composition and Mg/ Ca ratios of fossil (unstained) foraminifera recovered at carbonate-rich sites on the northern Hydrate Ridge reveals overprinting of the biogenic record by inorganic calcite with high Mg/Ca and anomalously low d 13 C values. Thus overprinting of the original isotopic composition of foraminifera by overgrowths or recrystallization at or below the sediment surface, rather than primary calcification in contact with 13 C depleted DIC, can explain extreme 13 C depletion observed in fossil foraminifera recovered from sites of active methane discharge.

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Section: Fluid Flow Regime and Pore Water Datasupporting

confidence: 62%

Is methane venting at the seafloor recorded by δ¹³C of benthic foraminifera shells?

et al. 2003

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“…This interpretation is supported by the anomalous 13C.depletio n in the dissolved ECO 2 of selected samples of pore fluids from Cores 8306-24, 8306-26, 8306-27, and 8708-02 of the underthrust ridge and 8408-04 from the toe of the continental slope ( Fig.6; Table III). We consider it particularly significant that certain carbon isotope values of the dissolved ECO2, between -23%0 and -34%0 PDB, are more negative than the minimum values of -22%0 measured for POC from this area (Hedges and Mann, 1979;Hedges and Van Green, 1982). The latter would be the lowest value that could reasonably be explained by addition of metabolic ZCO 2 solely from sedimentary POC sources (Claypool and Kaplan, 1974;Reeburgh, 1982).…”

Section: • -28mentioning

confidence: 93%

Methane-derived CO2 in pore fluids expelled from the Oregon subduction zone

Suess

Whiticar

1989

Palaeogeography, Palaeoclimatology, Palaeoecology

146

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Pore fluids extracted from near-surface sediments of the deformation front along the Oregon subduction zone have, in general, the dissolved nutrient pattern characteristic of bacterial sulfate reduction. However, in certain locations there are peculiar ammonium distributions and anomalously 13C_depleted dissolved ECO 2. These carbon isotope and nutrient patterns are attributed to the concurrent microbially-mediated oxidation of sedimentary organic matter (POC) and methane (CH4) originating from depth. In contrast to the oxidation of sedimentary organic matter in the sulfate zone, utilization of methane as the carbon source by sulfate-reducing bacteria would generate only half as much total carbon dioxide for each mole of sulfate consumed and would not generate any dissolved ammonium. The isotopically light ECO 2 released from methane oxidation depletes the total metabolic carbon dioxide pool. Therefore, NH~, ECO 2 and 6 j 3C of interstitial carbon dioxide in these pore fluids distinctly reflect the combined contributions of each of the two carbon substrates undergoing mineralization; i.e. methane and sedimentary organic matter. By appropriately partitioning the nutrient and substrate relationships, we calculate that in the area of the marginal ridge of the Oregon subduction zone as much as 30% of the ECO 2 in pore fluids may result from methane oxidation. The calculation also predicts that the carbon isotope signature of the carbon dioxide derived from methane is between-35%0 and-63%0 PDB. Such an isotopically light gas generated from within the accretionary complex could be the residue of a biogenic methane pool. Fluid advection is required to carry such methane from depth to the present nearsurface sediments. This mechanism is consistent with large-scale, tectonically-induced fluid transport envisioned for accreted sediments of the world's convergent plate boundaries.

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“…For the past few decades there has been considerable interest in understanding the source and fate of OM terr delivered to the LCS (Hedges and Parker, 1976;Hedges and Vangeen, 1982;Goñ i et al, 1997;Goñ i, 2003, 2004;McKee et al, 2004;Corbett et al, 2006;Bianchi et al, 2007aBianchi et al, ,b, 2009Sampere et al, 2008). The Mississippi River Delta is one of the most anthropogenically modified river systems in the world, where the shelf experiences the largest hypoxic events in the western Hemisphere (Rabalais et al, 2002a,b;Syvitski et al, 2009;Bianchi et al, 2010).…”

Section: Site Description and Samplingmentioning

confidence: 97%

A re-evaluation of the use of branched GDGTs as terrestrial biomarkers: Implications for the BIT Index

Smith

Bianchi

2012

Geochimica et Cosmochimica Acta

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A comparison of lignin and stable carbon isotope compositions in quaternary marine sediments

Cited by 39 publications

References 22 publications

Is methane venting at the seafloor recorded by δ¹³C of benthic foraminifera shells?

Is methane venting at the seafloor recorded by δ¹³C of benthic foraminifera shells?

Methane-derived CO2 in pore fluids expelled from the Oregon subduction zone

A re-evaluation of the use of branched GDGTs as terrestrial biomarkers: Implications for the BIT Index

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A comparison of lignin and stable carbon isotope compositions in quaternary marine sediments

Cited by 39 publications

References 22 publications

Is methane venting at the seafloor recorded by δ13C of benthic foraminifera shells?

Is methane venting at the seafloor recorded by δ13C of benthic foraminifera shells?

Methane-derived CO2 in pore fluids expelled from the Oregon subduction zone

A re-evaluation of the use of branched GDGTs as terrestrial biomarkers: Implications for the BIT Index

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Product

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Is methane venting at the seafloor recorded by δ¹³C of benthic foraminifera shells?

Is methane venting at the seafloor recorded by δ¹³C of benthic foraminifera shells?