Formation of pristane from α-tocopherol under simulated anoxic sedimentary conditions: A combination of biotic and abiotic degradative processes

Rontani, J.‐F.; Nassiry, Mina; Michotey, Valérie; Guasco, Sophie; Bonin, Patricia

doi:10.1016/j.gca.2009.09.028

Cited by 39 publications

(21 citation statements)

References 54 publications

(77 reference statements)

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“…This contrast may thus suggest a sedimentary contribution of pristane, as it is used in the former indices but not in the latter. While pristane and phytane are generally considered compounds produced via degradation of phytol (e.g., Didyk et al, 1978), this assumption for pristane has been questioned in oxygen-depleted sediments (e.g., Grossi et al, 1998;Rontani and Volkman, 2003;Rontani et al, 2010). The higher index 1 and index 3 values in below-OMZ-seep 1 and OMZ-seep 1 could indicate faster conversion of reactive phytol into a more refractory form (e.g., .…”

Section: Phytol-based Indicesmentioning

confidence: 99%

“…Thus, it is likely that there is a secondary source of pristane that does not involve the degradation of chlorophyll-a (for a review see Rontani and Bonin, 2011). Sources could include tocopherol degradation (Rontani et al, 2010) or input from archaeal lipids (Rowland, 1990). Even without the sedimentary input of pristane, index 2 does not show a preferential degradation of phytol with increasing SWI oxygen concentrations.…”

Section: Phytol-based Indicesmentioning

confidence: 99%

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The effect of meter-scale lateral oxygen gradients at the sediment-water interface on selected organic matter based alteration, productivity and temperature proxies

et al. 2012

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Abstract.A valid assessment of selective aerobic degradation on organic matter (OM) and its impact on OM-based proxies is vital to produce accurate environmental reconstructions. However, most studies investigating these effects suffer from inherent environmental heterogeneities. In this study, we used surface samples collected along two meterscale transects and one longer transect in the northeastern Arabian Sea to constrain initial OM heterogeneity, in order to evaluate selective aerobic degradation on temperature, productivity and alteration indices at the sediment-water interface. All of the studied alteration indices, the higher plant alkane index, alcohol preservation index, and diol oxidation index, demonstrated that they are sensitive indicators for changes in the oxygen regime. Several export production indices, a cholesterol-based stanol/stenol index and dinoflagellate lipid-and cyst-based ratios, showed significant (more than 20 %) change only over the lateral oxygen gradients. Therefore, these compounds do not exclusively reflect surface water productivity, but are significantly altered after deposition. Two of the proxies, glycerol dibiphytanyl glycerol tetraether-based TEX 86 sea surface temperature indices and indices based on phytol, phytane and pristane, did not show any trends related to oxygen. Nevertheless, unrealistic sea surface temperatures were obtained after application of the TEX 86 , TEX L 86 , and TEX H 86 proxies. The phytol-based ratios were likely affected by the sedimentary production of pristane. Our results demonstrate the selective impact of aerobic organic matter degradation on the lipid and palynomorph composition of surface sediments along a short lateral oxygen gradient and suggest that some of the investigated proxies may be useful tracers of changing redox conditions at the sediment-water interface.

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Section: Phytol-based Indicesmentioning

confidence: 99%

Section: Phytol-based Indicesmentioning

confidence: 99%

The effect of meter-scale lateral oxygen gradients at the sediment-water interface on selected organic matter based alteration, productivity and temperature proxies

et al. 2012

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“…However, due to other potential origins of both Pr (e.g. Rontani et al, 2010) and Ph, Pr/Ph values in the range of 0.8-3.0 are not recommended for indicating depositional redox conditions without corroborating evidence (Peters et al, 2005). Because only some samples in the dataset have a Pr/Ph value <0.8, the Pr/Ph ratio in this study is taken as suggestive of redox conditions.…”

Section: Paleoenvironmental Significance and Origin Of Mttcsmentioning

confidence: 99%

Paleosalinity significance of occurrence and distribution of methyltrimethyltridecyl chromans in the Upper Cretaceous Nenjiang Formation, Songliao Basin, China

Wang

Song

Yin

et al. 2011

Organic Geochemistry

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“…Additionally, pristane may also originate from tocopherols [25] and methyltrimethyltridecylchromans (MTTC) [26]. Considering the various sources of pristane and phytane, Rontani, et al [27] have suggested that Pr/Ph as redox indicator should be applied with care, because the results are not always reliable. Hence, it is proposed that the high Pr/Ph in the Ombilin oil shale is source dependent rather than redox sensitive.…”

Section: Depositional Environmentmentioning

confidence: 99%

Depositional Environment of the Sangkarewang Oil Shale, Ombilin Basin, Indonesia

2014

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Abstract. Five samples from a 56 m long drill core that was recovered from the lacustrine Sangkarewang oil shale have been studied by means of petrography and organic geochemistry in order to investigate the organic matter composition and depositional environment of the shale. The organic matter consisted of abundant lamalginite (30%, v/v) and a very limited amount of vitrinite, suggesting an aquatic depositional environment with minor terrestrial influence. Organic geochemical analysis exhibited the dominance of pristane, phytane, and generally n-alkane compounds. These compounds may have originated mostly from aquatic photosynthetic organisms. The oil shale was likely deposited in an anoxic lake environment as suggested by the presence of framboidal pyrite (6%, v/v) and preserved organic matter with a total organic carbon (TOC) percentage of about 4.9%. The pristane/phytane ratio was relatively high (about 3.9) and thought to be source sensitive rather than redox sensitive. Hopanoid and aryl isoprenoid compounds were present in minor amounts. The latter compounds are interpreted to be derived from green sulfur bacteria dwelling in an anoxic environment with the presence of H 2 S in bottom water.

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Formation of pristane from α-tocopherol under simulated anoxic sedimentary conditions: A combination of biotic and abiotic degradative processes

Cited by 39 publications

References 54 publications

The effect of meter-scale lateral oxygen gradients at the sediment-water interface on selected organic matter based alteration, productivity and temperature proxies

The effect of meter-scale lateral oxygen gradients at the sediment-water interface on selected organic matter based alteration, productivity and temperature proxies

Paleosalinity significance of occurrence and distribution of methyltrimethyltridecyl chromans in the Upper Cretaceous Nenjiang Formation, Songliao Basin, China

Depositional Environment of the Sangkarewang Oil Shale, Ombilin Basin, Indonesia

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