An Integrated Biochemical, Geochemical, and Sedimentological Study of Organic Diagenesis in Sediments from Leg 112

Patience, R.L.; Clayton, Chris; Kearsley, A. T.; Rowland, Steven J.; Bishop, Andrew N.; Rees, A. W. G.; Bibby, K G; Hopper, A C

doi:10.2973/odp.proc.sr.112.191.1990

Cited by 35 publications

(31 citation statements)

References 35 publications

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“…Average organic carbon levels over the top 1 m of sediment were 3.6%. This compares with 4.0%-5.1% between 0.30 and 0.89 mbsf (ten Haven et al, 1990;Patience et al, 1990) in Peru Margin sediments, which display greater numbers of dividing cells (Table 1). Conversely, between 1.5 and 2 mbsf, the average organic carbon concentration was 2.6%, compared to 1.6% over the same depth range in the Japan Sea (Ingle, Suyehiro, von Breymann, et al, 1990) which had much lower numbers of dividing cells at 0.03 mbsf (Table 1).…”

Section: Resultsmentioning

confidence: 99%

Bacterial Profiles in Deep Sediments of the Santa Barbara Basin, Site 893

Cragg¹,

Parkes²,

Fry³

et al. 1995

Proceedings of the Ocean Drilling Program

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Bacterial depth profiles were obtained from high-organic-load sediments (water depth 538 m) to a depth of 68.28 m below seafloor. Using the Acridine Orange Direct Count (AODC) technique, near-surface bacterial populations were 1.27 × 10 9 cells/ cm 3 . Numbers of bacteria decreased rapidly to 4.77 × 10 6 cells/cm 3 at 12 mbsf and then more slowly to 2.51 × 10 6 cells/cm 3 at 68.28 mbsf (505-fold decrease). Dividing cells represented approximately 10% of the total count but decreased at a greater rate (850-fold). There was an abrupt change in the rate of total bacterial population decrease at approximately 13 mbsf. Bacterial numbers were strongly correlated (P « 0.002) with total organic carbon. Near-surface concentrations of organic carbon rapidly decreased from approximately 3.6% to 2.0% at 13 mbsf, and thereafter remained at 1.5%-2.0% to the base of the core at 68.28 mbsf, indicating a high level of recalcitrance. The changes in the rate of bacterial population decrease with depth may be a response to increasingly recalcitrant organic carbon. High levels of methane (4100 µmol/L) were found at 9.0 mbsf, although the maximum concentration present in the sediment at this site may be in an unsampled horizon above this depth. At greater depth, methane concentrations were still high (>IOOO µmol/L), and although this area has many seeps of oil and gas, the C|/C 2+ ratios indicate a biogenic rather than a fhermogenic source.This work represents the first detailed microbiological analysis of deep sediment layers from the Santa Barbara Basin.

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Section: Resultsmentioning

confidence: 99%

Bacterial Profiles in Deep Sediments of the Santa Barbara Basin, Site 893

Cragg¹,

Parkes²,

Fry³

et al. 1995

Proceedings of the Ocean Drilling Program

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“…The utility of OS04 impregnation to locate organic matter has been illustrated in a wide range of recent and ancient terrestrial sedimentary rocks (Aplin et al, 1992;Bishop et al, 1992;Patience et al, 1990).…”

Section: Samples and Analytical Proceduresmentioning

confidence: 99%

“…The carbonaceous chondrites contain a wide variety of water-soluble organic compounds (Cronin and Chang, 1993;Sephton, 2002). During aqueous alteration on the meteorite parent body, clay minerals may have trapped and concentrated organic compounds thereby promoting polymerization reactions (Ponnamperuma et al, 1982). Extrapolating forward from the snapshotofprebioticmolecularevolutionrecordedin carbonaceous chondrites, the accumulation, protection and consequent polymerization oforganic species within a clay-mineral matrix may have facilitated the development and preservation of primitive biopolymers that laid the foundations for early life.…”

Section: Significance For Prebiotic Molecular Evolutionmentioning

confidence: 99%

“…Minerals have also been linked with the development of complex organic networks (Ponnamperuma et al, 1982), considered to be the forerunners of biomacromolecules. Understanding the relationships and interdependence oforganic and inorganic components is essential for comprehending the processes and mechanisms involved in the evolution oforganic material in the early solar system.…”

Section: Introductionmentioning

confidence: 99%

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Clay mineral‐organic matter relationships in the early solar system

Pearson

Sephton

Kearsley

et al. 2002

Meteorit & Planetary Scien

127

107

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Abstract-As the solar system formed, it inherited and perpetuated a rich organic chemistry, the molecular products of which are preserved in ancient extraterrestrial objects such as carbonaceous chondrites. These organic-rich meteorites provide a valuable and tangible record of the chemical steps taken towards the origin of life in the early solar system. Chondritic organic matter is present in the inorganic meteorite matrix which, in the CM and CI chondrites, contains evidence ofalteration by liquid water on the parent asteroid. An unanswered and fundamental question is to what extent did the organic matter and inorganic products ofaqueous alteration interact or display interdependence? We have used an organic labelling technique to reveal that the meteoritic organic matter is strongly associated with clay minerals. This association suggests that clay minerals may have had an important trapping and possibly catalytic role in chemical evolution in the early solar system prior to the origin of life on the early Earth.

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“…[14] Modest increases in the C/N ratio independent of changes in organic matter type during diagenesis are normal under most sedimentary conditions [Freudenthal et al, 2001;Muller, 1977;Patience et al, 1990]. Sedimentary C/N ratios of 10-15 are typical of low-oxygen, high productivity environments in modern upwelling systems where sedi- mentary organic matter is predominantly marine such as offshore Peru and Namibia [Twichell et al, 2002] as well as euxinic environments such as the Holocene Black Sea, (J. Fulton and M. A.…”

Section: Geochemical Patternsmentioning

confidence: 99%

Nitrogen cycling during the Cretaceous, Cenomanian‐Turonian Oceanic Anoxic Event II

Junium

Arthur

2007

Geochem Geophys Geosyst

148

135

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Low δ15N values, ranging from +1.2‰ to −3.9‰, and atomic carbon/nitrogen (C/N) ratios of 25–50 are characteristic of “black shales” deposited during the Cenomanian‐Turonian boundary interval and Oceanic Anoxic Event II (OAE II). An observed antithetic relationship between C/N ratios and δ15N could suggest a predominance of terrestrially derived organic matter or a diagenetic control on δ15N variability shifting bulk δ15N values lower. However, Hydrogen Indices (HI) generally >450, and a positive correlation of HI with C/N mitigates against a significant terrestrial organic matter fraction. High C/N values are likely the result preferential degradation of labile, N‐rich compounds during early diagenesis and loss of N as ammonium from sediments through time. A hypothetical model that considers the degradation of a 15N‐enriched labile protein fraction yields only small, 1–2‰ negative shifts in δ15N. However, 15N depletion during diagenesis is contrary to normal isotope kinetics which should result in 15N enrichment of bulk organic matter. Therefore we conclude that the bulk δ15N values in this study reflect primary changes in the nitrogen cycle. The δ15N data support the hypothesis of expanded nitrogen fixation driven by upwelling of nutrient‐nitrogen poor, phosphorus replete waters during OAE II and from the mid‐Cenomanian to Santonian at Demerara Rise. The low δ15N values, which are significantly lower than bulk δ15N values in modern regions where nitrogen fixation is known to be important, probably result from a more significant fraction of dissolved inorganic nitrogen being produced by nitrogen fixation. During the peak of OAE II a marked shift to lower δ15N values is observed. This shift possibly reflects greater utilization of 15N‐depleted ammonium during a chemocline upward excursion (CUE). Dominance of low δ15N values from other periods of more widespread marine anoxia is likely the result of similar processes.

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An Integrated Biochemical, Geochemical, and Sedimentological Study of Organic Diagenesis in Sediments from Leg 112

Cited by 35 publications

References 35 publications

Bacterial Profiles in Deep Sediments of the Santa Barbara Basin, Site 893

Bacterial Profiles in Deep Sediments of the Santa Barbara Basin, Site 893

Clay mineral‐organic matter relationships in the early solar system

Nitrogen cycling during the Cretaceous, Cenomanian‐Turonian Oceanic Anoxic Event II

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