Limits in pyrolysis–GC–MS analysis of kerogen isolated from Archean cherts

Bourbin, Mathilde; Derenne, Sylvie; Robert, François

doi:10.1016/j.orggeochem.2012.08.004

Cited by 8 publications

(4 citation statements)

References 7 publications

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“…The existence of sulfate-reducing bacteria has been proposed by the pyrolysis fragments of the organic matter (Derenne et al 2008). However, the potential risk of post-depositional and experimental contamination has been found in the pyrolysis analysis of the isolated Archean organic matter (e.g., Bourbin et al 2012). The presence of ancient methanogenic archaea has been inferred from the fluid inclusions in the silica veins containing 13 C-depleted methane (Ueno et al 2006), although the abiotic origin of the methane has also been proposed (Sherwood-Lollar and McCollom 2006).…”

Section: Origin Of the Carbonaceous Mattermentioning

confidence: 99%

“…The chemical analysis of carbonaceous matter is necessary for understanding its origin and characteristics. However, the bulk analysis of isolated organic matter generally involves the potential risk of post-depositional and experimental contamination of the organic matter (e.g., Brocks et al 1999;Derenne et al 2008;Rasmussen et al 2008;Bourbin et al 2012). In situ analysis is a more reliable technique that avoids such contamination problems and extracts chemical signatures specific to individual microstructures in petrographic thin sections (e.g., House et al 2000House et al , 2013Kudryavtsev et al 2001;Ueno et al 2001;Schopf et al 2002Schopf et al , 2005Igisu et al 2006Igisu et al , 2009van Zuilen et al 2007;Wacey et al 2011;Lepot et al 2013; Williford et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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FTIR microspectroscopy of carbonaceous matter in ~ 3.5 Ga seafloor hydrothermal deposits in the North Pole area, Western Australia

Igisu

Ueno

Takai

2018

Prog Earth Planet Sci

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Carbonaceous matter in~3.5 Ga hydrothermal vein deposits from the Dresser Formation, Western Australia, was analyzed using Fourier transform infrared (FTIR) microspectroscopy. Based on the spectroscopy, the carbonaceous matter was mainly composed of disordered aromatic structures, with minor aliphatic C-H functional groups. Spatially resolved analysis supports that the aliphatic C-H signatures are derived from kerogenous macromolecule and not from free bitumen or other artificial sources. The intensity ratios of the asymmetric aliphatic CH 3 to the asymmetric aliphatic CH 2 (R 3/2 value) in the carbonaceous clots range from 0.22 to 0.51. Thermal alteration may increase or not change the R 3/2 value of organic matter, as suggested by previous experiments, but it is unlikely to be the cause of the substantially lower R 3/2 values when compared with those of primary organic matter. In particular, the low R 3/2 values (<~0.4) suggest that the carbonaceous matter mainly contains aliphatic C-H bonds derived from bacterial cells. The carbonaceous clots may have been possibly produced by abiotic reaction such as Fischer-Tropsch-type (FTT) synthesis. However, the organic matter source only produced by the FTT synthesis is inconsistent with the R 3/2 values for the analyzed carbonaceous clots. The results obtained by combining these spectroscopic features of the carbonaceous clots together with the previously reported isotopic features may possibly suggest that both bacteria and archaea were colonized in thẽ 3.5 Ga Dresser hydrothermal system.

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Section: Origin Of the Carbonaceous Mattermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

FTIR microspectroscopy of carbonaceous matter in ~ 3.5 Ga seafloor hydrothermal deposits in the North Pole area, Western Australia

Igisu

Ueno

Takai

2018

Prog Earth Planet Sci

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“…Molecular characterization of Archean CM has recently been recognized as a promising tool with which to discriminate between biotic and abiotic CM (Brocks et al , 2003 ; Marshall et al , 2007 ; Derenne et al , 2008 ). Unfortunately, in most samples, multiple sources of postdepositional CM and the extensive impact of metamorphism have resulted in the masking or elimination of molecular structures and a lack of univocal molecular biosignatures (Bourbin et al , 2012a ; French et al , 2015 ). Quantifying the degree of alteration of Archean CM was thus of prime interest in the search for molecular biosignatures in the oldest cherts on Earth (Marshall et al , 2012 ).…”

Section: Introductionmentioning

confidence: 99%

The Raman-Derived Carbonization Continuum: A Tool to Select the Best Preserved Molecular Structures in Archean Kerogens

et al. 2016

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The search for indisputable traces of life in Archean cherts is of prime importance. However, their great age and metamorphic history pose constraints on the study of molecular biomarkers. We propose a quantitative criterion to document the thermal maturity of organic matter in rocks in general, and Archean rocks in particular. This is definitively required to select the best candidates for seeking non-altered sample remnants of life. Analysis of chemical (Raman spectroscopy, 13C NMR, elemental analysis) and structural (HRTEM) features of Archean and non-Archean carbonaceous matter (CM) that was submitted to metamorphic grades lower than, or equal to, that of greenschist facies showed that these features had all undergone carbonization but not graphitization. Raman-derived quantitative parameters from the present study and from literature spectra, namely, R1 ratio and FWHM-D1, were used to draw a carbonization continuum diagram showing two carbonization stages. While non-Archean samples can be seen to dominate the first stage, the second stage mostly consists of the Archean samples. In this diagram, some Archean samples fall at the boundary with non-Archean samples, which thus demonstrates a low degree of carbonization when compared to most Archean CM. As a result, these samples constitute candidates that may contain preserved molecular signatures of Archean CM. Therefore, with regard to the search for the oldest molecular traces of life on Earth, we propose the use of this carbonization continuum diagram to select the Archean CM samples. Key Words: Archean—Early life—Kerogen—Raman spectroscopy—Carbonization. Astrobiology 16, 407–417.

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“…Our method can potentially be used to resolve the biogenicity of data already in hand. An important example is the 3.5 Ga Apex chert from the Pilbara Craton in Western Australia, whose purported biogenicity has evoked significant debate ( 50 , 51 ). In addition, samples measured by the Pyr-GC-MS instruments on the Mars Viking lander and the Curiosity rover ( 34 , 43 , 52 ) deserve new evaluation.…”

Section: Discussionmentioning

confidence: 99%

A robust, agnostic molecular biosignature based on machine learning

Cleaves,

Hystad,

Prabhu

et al. 2023

Proc. Natl. Acad. Sci. U.S.A.

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The search for definitive biosignatures—unambiguous markers of past or present life—is a central goal of paleobiology and astrobiology. We used pyrolysis–gas chromatography coupled to mass spectrometry to analyze chemically disparate samples, including living cells, geologically processed fossil organic material, carbon-rich meteorites, and laboratory-synthesized organic compounds and mixtures. Data from each sample were employed as training and test subsets for machine-learning methods, which resulted in a model that can identify the biogenicity of both contemporary and ancient geologically processed samples with ~90% accuracy. These machine-learning methods do not rely on precise compound identification: Rather, the relational aspects of chromatographic and mass peaks provide the needed information, which underscores this method’s utility for detecting alien biology.

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Limits in pyrolysis–GC–MS analysis of kerogen isolated from Archean cherts

Cited by 8 publications

References 7 publications

FTIR microspectroscopy of carbonaceous matter in ~ 3.5 Ga seafloor hydrothermal deposits in the North Pole area, Western Australia

FTIR microspectroscopy of carbonaceous matter in ~ 3.5 Ga seafloor hydrothermal deposits in the North Pole area, Western Australia

The Raman-Derived Carbonization Continuum: A Tool to Select the Best Preserved Molecular Structures in Archean Kerogens

A robust, agnostic molecular biosignature based on machine learning

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