Carbon, nitrogen, and sulfur geochemistry of Archean and Proterozoic shales from the Kaapvaal Craton, South Africa

Watanabe, Yumiko; Naraoka, Hiroshi; Wronkiewicz, David J.; Condie, Kent C.; Ohmoto, Hiroshi

doi:10.1016/s0016-7037(97)00164-6

Cited by 100 publications

(33 citation statements)

References 40 publications

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“…Incorporation of such 13 C-depleted CO 2 (or CH 4 ) into biological activity produces organic matter with extremely light δ 13 C values (<-35‰). Many previous investigators suggested that diagenetic or metamorphic degradation of organic matter causes the shift of δ 13 C org compositions towards heavier values, and the shift has been related to the H/C ratio of the kerogen Schidlowski, 1988;Watanabe et al, 1997). The disadvantage of carbon isotope analysis using the laser microprobe is that the H/C ratios of kerogen cannot be determined on the same point where the δ 13 C org values are determined.…”

Section: Significance Of Carbon Isotope Compositionsmentioning

confidence: 99%

Sulfur and carbon isotope analyses of the 2.7Ga Jeerinah Formation, Fortescue Group, Australia.

et al. 2000

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Sulfur and carbon isotope ratios have been determined on carbonaceous shales of the 2.7 Ga Jeerinah Formation, Hamersley Group, Australia. The analyses were performed using the Nd-YAG laser microprobe method.The δ 13 C (PDB) values of organic matter range from -38.3‰ to -35.1‰ with an average of -37.0‰ (44 analyses). These carbon isotope compositions support the previously proposed hypothesis that methanogens and methanotrophs were involved in the carbon cycles in the 2.7 Ga Hamersley ocean. Sulfur isotope compositions are ranging from +0.4‰ to +10.2‰ with an average of +4.6‰ (90 analyses). A notable feature is variable δ 34 S values within a micro-scale area; approximately 6 to 7‰ variations of δ 34 S values were detected within 5 × 5 mm areas. Such δ 34 S variations clearly indicate that pyrites in the Jeerinah shales were formed as a result of the sulfate reduction. This suggests that the 2.7 Ga Hamersley ocean contained appreciable amount of dissolved sulfate, opposing to the previously popular H 2 S-rich ocean model. Because of no evidence for the hydrothermal alterration on the examined samples, pyrites in the 2.7 Ga Jeerinah shales were most likely formed by the biological sulfate reduction in sediments.ganisms were active in the 2.7 Ga ocean and that these organisms played an important role in the global carbon cycle. These suggestions were based on the discovery of organic matter with extremely light δ 13 C values, -60 to -40‰, in some sedimentary rocks in the Hamersley Basin in Australia, in the Abitibi greenstone belt in Canada and the Transvaal basin in South Africa (Hayes et al

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Section: Significance Of Carbon Isotope Compositionsmentioning

confidence: 99%

Sulfur and carbon isotope analyses of the 2.7Ga Jeerinah Formation, Fortescue Group, Australia.

et al. 2000

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“…Many lines of evidence have been presented to suggest that the rise in atmospheric oxygen levels-termed the Great Oxidation Event (GOE, after Holland, 2002)-took place some time during the Paleoproterozoic (2.3 to 1.8 Ga) (Cloud, 1968(Cloud, , 1972(Cloud, , 1973Walker, 1977;Walker and Brimblecombe, 1985;Kasting, 1987;Holland, 1984Holland, , 1994Holland, , 1999. Contradicting this, it is also proposed that atmospheric oxygen reached high levels and remained constant from the early Archean (from about 4 Ga) onwards (Dimroth and Kimberley, 1976;Clemmey and Badham, 1982;Towe, 1990;Ohmoto, 1992Ohmoto, , 1996Ohmoto, , 1997Ohmoto, , 2003Watanabe et al, 1997Watanabe et al, , 2000Watanabe et al, , 2004Lasaga and Ohmoto, 2002). In the following sections, we discuss the status of various indicators such as banded iron formations (BIFs), red beds, detrital heavy minerals (uraninite, pyrite, etc.…”

Section: Timing Of Atmospheric Oxygen Risementioning

confidence: 96%

Emerging views on the evolution of atmospheric oxygen during the Precambrian

Sreenivas

Murakami

2005

Journal of Mineralogical and Petrological Sciences

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The oxygenation of the atmosphere produced some irreversible changes in the Earth's history, including evolution of higher biological forms. Several aspects of this important process, such as its timing and causes, have remained subjects of debate. The present review is an attempt to provide an update on issues related to the evolution of atmospheric oxygen during the Precambrian. It is generally believed that the amount of atmospheric oxygen increased during the Paleoproterozoic despite the fact that photosynthesis originated much earlier in the Earth's history. The pattern of Fe retention in paleosols and the record of mass independent fractionation in sulfur isotopes confirm that the transition to more oxidizing conditions took place during the Paleoproterozoic.Various mechanisms, ranging from an increase in the sources of oxygen to a decrease in its sinks, have been envisaged as processes causing the oxygen rise during the Paleoproterozoic. Conventionally, it is believed that the burial of photosynthetic carbon has allowed the establishment of oxygen. However, the transition in mantle oxidation states and the escape of hydrogen during photolysis of methane of biogenic origin have also been suggested as having played an important role in the establishment of free molecular oxygen in the atmosphere hydrosphere system. The coincidence of timing of the oxygen rise and the positive excursions in carbon isotope compositions of carbonate rocks during the Paleoproterozoic suggests an important role for the carbon cycle in atmospheric oxygen evolution.Better quantitative modeling of atmospheric oxygen levels may be essential to allow full comprehension of the timing, causes and consequences of the oxygen rise in the Earth's history. Quantitative modeling is essential as it can lead to an unraveling of the co evolutionary nature of the surface environment and the biosphere of the Earth.

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“…The N/C atomic ratio has often been used as a proxy for bulk OM preservation status (Watanabe et al, 1997;Beaumont and Robert, 1999). Consequently, it has also been used as a proxy for the geochemical preservation at the scale of individual Precambrian microfossils (Oehler et al, 2009(Oehler et al, , 2010Alleon et al, 2016).…”

Section: Towards a Framework To Evaluate The Significance Of In Situ mentioning

confidence: 99%

“…In parallel, it has been demonstrated that the emission of secondary ionic species used to monitor elements such as C or N can also be quantitatively associated with the geochemical elemental composition of both bulk OM (Thomen et al, 2014;Alleon et al, 2016) and individual organicwalled microfossils (Oehler et al, 2009(Oehler et al, , 2010Delarue et al, 2017). For instance, the 12 C 14 N − / 12 C 2 − secondary molecular ion ratio allows the determination of the N/C atomic ratio (Thomen et al, 2014), which is often used as a proxy for OM degradation during early diagenesis (Watanabe et al, 1997;Beaumont and Robert, 1999). However, the quantitative capabilities of NanoSIMS have been little used since some analytical biases may significantly alter 12 C 14 N − and 12 C 2 − emissions.…”

Section: Introductionmentioning

confidence: 99%

Can NanoSIMS probe quantitatively the geochemical composition of ancient organic-walled microfossils? A case study from the early Neoproterozoic Liulaobei Formation

Delarue

Robert

Tartèse

et al. 2018

Precambrian Research

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Assessing the biogenicity of Precambrian putative remnants of life requires solid criteria. Among possible criteria, searching for evidence of pristine biological signatures and identifying various biological organic matter (OM) precursors in close association with microfossil morphology are of interest. Nano-scale Secondary Ion Mass Spectrometry (NanoSIMS) can provide a quantitative geochemical proxy at the scale of the individual microfossil but its use has remained limited because of potential analytical biases related to matrix effects and microtopography that may result in inaccurate NanoSIMS-derived measurement. No study so far has assessed whether these potential analytical biases were strong enough to preclude any identification of pristine OM degradation products and of organic precursors in ancient sediments. In this study, we characterized the geochemical composition of organic-walled microfossils from the early Neoproterozoic Liulaobei Formation in North China using NanoSIMS. The 12 CH − / 12 C 2 − ionic ratio allows us to distinguish filament from spheroid acritarchs, revealing the co-occurrence of two distinct pristine OM signatures that differ by their H and/or aliphatic contents. In addition, NanoSIMS data show that morphological degradation was tightly linked to a loss of H and/or hydrogenated organic compounds in spheroid acritarchs. In contrast, in situ N/C atomic ratios are homogeneous across all organic-walled microfossils studied. Although highly coherent with Proterozoic N/C atomic ratios from the literature, such homogeneity may alternatively reflect (i) a similar N content for different organic precursors or (ii) an extensive homogenization related to early degradation. Overall, these data obtained on microfossils from the Proterozoic Liulaobei Formation are the first to demonstrate that the quantitative capability of NanoSIMS can be used to track ancient OM precursors and to probe the effects of degradation on pristine OM. These findings open up tremendous perspectives and put forward new criteria for assessing the biogenicity of the putative early traces of life found in Archean metasediments.

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Carbon, nitrogen, and sulfur geochemistry of Archean and Proterozoic shales from the Kaapvaal Craton, South Africa

Cited by 100 publications

References 40 publications

Sulfur and carbon isotope analyses of the 2.7Ga Jeerinah Formation, Fortescue Group, Australia.

Sulfur and carbon isotope analyses of the 2.7Ga Jeerinah Formation, Fortescue Group, Australia.

Emerging views on the evolution of atmospheric oxygen during the Precambrian

Can NanoSIMS probe quantitatively the geochemical composition of ancient organic-walled microfossils? A case study from the early Neoproterozoic Liulaobei Formation

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