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Woltz CR, Anderson RP, Tosca NJ, Porter SM. The role of clay minerals in the preservation of Precambrian organic-walled microfossils. GEOBIOLOGY 2023; 21:708-724. [PMID: 37724627 DOI: 10.1111/gbi.12573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 06/20/2023] [Accepted: 08/12/2023] [Indexed: 09/21/2023]
Abstract
Precambrian organic-walled microfossils (OWMs) are primarily preserved in mudstones and shales that are low in total organic carbon (TOC). Recent work suggests that high TOC may hinder OWM preservation, perhaps because it interferes with chemical interactions involving certain clay minerals that inhibit the decay of microorganisms. To test if clay mineralogy controls OWM preservation, and if TOC moderates the effect of clay minerals, we compared OWM preservational quality (measured by pitting on fossil surfaces and the deterioration of wall margins) to TOC, total clay, and specific clay mineral concentrations in 78 shale samples from 11 lithologic units ranging in age from ca. 1650 to 650 million years ago. We found that the probability of finding well-preserved microfossils positively correlates with total clay concentrations and confirmed that it negatively correlates with TOC concentrations. However, we found no evidence that TOC influences the effect of clay mineral concentrations on OWM preservation, supporting an independent role of both factors on preservation. Within the total clay fraction, well-preserved microfossils are more likely to occur in shales with high illite concentrations and low berthierine/chamosite concentrations; however, the magnitude of their effect on preservation is small. Therefore, there is little evidence that bulk clay chemistry is important in OWM preservation. Instead, we propose that OWM preservation is largely regulated by physical properties that isolate organic remains from microbial degradation such as food scarcity (low TOC) and low sediment permeability (high total clay content): low TOC increases the diffusive distances between potential carbon sources and heterotrophic microbes (or their degradative enzymes), while high clay concentrations reduce sediment pore space, thereby limiting the diffusion of oxidants and degradative enzymes to the sites of decay.
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Affiliation(s)
- C R Woltz
- Department of Earth Science, University of California, Santa Barbara, California, USA
- Department of Earth and Planetary Sciences, Stanford University, Stanford, California, USA
| | - R P Anderson
- All Souls College, University of Oxford, Oxford, UK
- Department of Earth Sciences, University of Oxford, Oxford, UK
| | - N J Tosca
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - S M Porter
- Department of Earth Science, University of California, Santa Barbara, California, USA
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2
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Alleon J, Flannery DT, Ferralis N, Williford KH, Zhang Y, Schuessler JA, Summons RE. Organo-mineral associations in chert of the 3.5 Ga Mount Ada Basalt raise questions about the origin of organic matter in Paleoarchean hydrothermally influenced sediments. Sci Rep 2019; 9:16712. [PMID: 31723181 PMCID: PMC6853986 DOI: 10.1038/s41598-019-53272-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 10/30/2019] [Indexed: 11/27/2022] Open
Abstract
Hydrothermal and metamorphic processes could have abiotically produced organo-mineral associations displaying morphological and isotopic characteristics similar to those of fossilized microorganisms in ancient rocks, thereby leaving false-positive evidence for early life in the geological record. Recent studies revealed that geologically-induced alteration processes do not always completely obliterate all molecular information about the original organic precursors of ancient microfossils. Here, we report the molecular, geochemical, and mineralogical composition of organo-mineral associations in a chert sample from the ca. 3.47 billion-year-old (Ga) Mount Ada Basalt, in the Pilbara Craton, Western Australia. Our observations indicate that the molecular characteristics of carbonaceous matter are consistent with hydrothermally altered biological organics, although significantly distinct from that of organic microfossils discovered in a chert sample from the ca. 3.43 Ga Strelley Pool Formation in the same area. Alternatively, the presence of native metal alloys in the chert, previously believed to be unstable in such hydrothermally influenced environments, indicates strongly reducing conditions that were favorable for the abiotic formation of organic matter. Drawing definitive conclusions about the origin of most Paleoarchean organo-mineral associations therefore requires further characterization of a range of natural samples together with experimental simulations to constrain the molecular composition and geological fate of hydrothermally-generated condensed organics.
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Affiliation(s)
- Julien Alleon
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
- Now at Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland.
| | - David T Flannery
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Nicola Ferralis
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Kenneth H Williford
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Yong Zhang
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | | | - Roger E Summons
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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3
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Wiemann J, Fabbri M, Yang TR, Stein K, Sander PM, Norell MA, Briggs DEG. Fossilization transforms vertebrate hard tissue proteins into N-heterocyclic polymers. Nat Commun 2018; 9:4741. [PMID: 30413693 PMCID: PMC6226439 DOI: 10.1038/s41467-018-07013-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 10/10/2018] [Indexed: 02/06/2023] Open
Abstract
Vertebrate hard tissues consist of mineral crystallites within a proteinaceous scaffold that normally degrades post-mortem. Here we show, however, that decalcification of Mesozoic hard tissues preserved in oxidative settings releases brownish stained extracellular matrix, cells, blood vessels, and nerve projections. Raman Microspectroscopy shows that these fossil soft tissues are a product of diagenetic transformation to Advanced Glycoxidation and Lipoxidation End Products, a class of N-heterocyclic polymers generated via oxidative crosslinking of proteinaceous scaffolds. Hard tissues in reducing environments, in contrast, lack soft tissue preservation. Comparison of fossil soft tissues with modern and experimentally matured samples reveals how proteinaceous tissues undergo diagenesis and explains biases in their preservation in the rock record. This provides a target, focused on oxidative depositional environments, for finding cellular-to-subcellular soft tissue morphology in fossils and validates its use in phylogenetic and other evolutionary studies.
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Affiliation(s)
- Jasmina Wiemann
- Department of Geology & Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT, 06511, USA.
| | - Matteo Fabbri
- Department of Geology & Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT, 06511, USA
| | - Tzu-Ruei Yang
- Steinmann Institute for Geology, Mineralogy, and Paleontology, University of Bonn, Nussallee 8, 53115, Bonn, Germany
| | - Koen Stein
- Earth System Sciences AMGC, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
| | - P Martin Sander
- Steinmann Institute for Geology, Mineralogy, and Paleontology, University of Bonn, Nussallee 8, 53115, Bonn, Germany
- Dinosaur Institute, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA, 90007, USA
| | - Mark A Norell
- Division of Vertebrate Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY, 10024-5192, USA
| | - Derek E G Briggs
- Department of Geology & Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT, 06511, USA
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4
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Igisu M, Yokoyama T, Ueno Y, Nakashima S, Shimojima M, Ohta H, Maruyama S. Changes of aliphatic C-H bonds in cyanobacteria during experimental thermal maturation in the presence or absence of silica as evaluated by FTIR microspectroscopy. GEOBIOLOGY 2018; 16:412-428. [PMID: 29869829 DOI: 10.1111/gbi.12294] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Accepted: 03/16/2018] [Indexed: 06/08/2023]
Abstract
Aliphatic C-H bonds are one of the major organic signatures detected in Proterozoic organic microfossils, and their origin is a topic of interest. To investigate the influence of the presence of silica on the thermal alteration of aliphatic C-H bonds in prokaryotic cells during diagenesis, cyanobacteria Synechocystis sp. PCC6803 were heated at temperatures of 250-450°C. Changes in the infrared (IR) signals were monitored by micro-Fourier transform infrared (FTIR) spectroscopy. Micro-FTIR shows that absorbances at 2,925 cm-1 band (aliphatic CH2 ) and 2,960 cm-1 band (aliphatic CH3 ) decrease during heating, indicating loss of the C-H bonds, which was delayed by the presence of silica. A theoretical approach using solid-state kinetics indicates that the most probable process for the aliphatic C-H decrease is three-dimensional diffusion of alteration products under both non-embedded and silica-embedded conditions. The extrapolation of the experimental results obtained at 250-450°C to lower temperatures implies that the rate constant for CH3 (kCH3 ) is similar to or lower than that for CH2 (kCH2 ; i.e., CH3 decreases at a similar rate or more slowly than CH2 ). The peak height ratio of 2,960 cm-1 band (CH3 )/2,925 cm-1 band (CH2 ; R3/2 values) either increased or remained constant during the heating. These results reveal that the presence of silica does affect the decreasing rate of the aliphatic C-H bonds in cyanobacteria during thermal maturation, but that it does not significantly decrease the R3/2 values. Meanwhile, studies of microfossils suggest that the R3/2 values of Proterozoic prokaryotic fossils from the Bitter Springs Group and Gunflint Formation have decreased during fossilization, which is inconsistent with the prediction from our experimental results that R3/2 values did not decrease after silicification. Some process other than thermal degradation, possibly preservation of specific classes of biomolecules with low R3/2 values, might have occurred during fossilization.
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Affiliation(s)
- Motoko Igisu
- School of Life Science and Technology, Tokyo Institute of Technology, Kanagawa, Japan
| | - Tadashi Yokoyama
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
| | - Yuichiro Ueno
- Department of Subsurface Geobiology Analysis and Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa, Japan
- Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo, Japan
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
| | - Satoru Nakashima
- Department of Earth and Space Science, Osaka University, Osaka, Japan
| | - Mie Shimojima
- School of Life Science and Technology, Tokyo Institute of Technology, Kanagawa, Japan
| | - Hiroyuki Ohta
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Kanagawa, Japan
| | - Shigenori Maruyama
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
- Novosibirsk State University, Novosibirsk, Russia
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Muscente AD, Czaja AD, Tuggle J, Winkler C, Xiao S. Manganese Oxides Resembling Microbial Fabrics and Their Implications for Recognizing Inorganically Preserved Microfossils. ASTROBIOLOGY 2018; 18:249-258. [PMID: 29570411 DOI: 10.1089/ast.2017.1699] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In the search for microfossils of early life on Earth, the demonstration of biogenicity is paramount. Traditionally, only syngenetic structures with cellular elaboration, hollow sheaths/cell walls, and indigenous kerogen have been considered bona fide fossils. Recent reports of inorganically preserved microfossils represent a shift from this practice. Such a shift, if accompanied by a robust set of biogenicity criteria, could have profound implications for the identification of biosignatures on early Earth and extraterrestrial bodies. Here, we reaffirm the conventional criteria by examining aggregates of inorganic filaments from the Pilbara region of Western Australia. These aggregates are preserved in bedded chert, and the filaments measure up to 1 μm in diameter and 100 μm in length. The aggregates superficially resemble kerogenous microbial fabrics and mycelial organisms. However, the filaments consist of manganese oxide, lack cellular elaboration, and show no evidence for hollow sheaths or cell walls. We conclude that the filaments are fibrous minerals of abiotic origin. The similarities between these pseudofossils and some filamentous fossils highlight the need for strict application of the conventional criteria for recognizing microfossils. In the absence of kerogen, morphologically simple structures should, at least, show evidence of cellular features to be considered bona fide fossils. Key Words: Fossil-Manganese oxide-Pilbara-Precambrian-Pseudofossil. Astrobiology 18, 249-258.
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Affiliation(s)
- A D Muscente
- 1 Department of Earth and Planetary Sciences, Harvard , Cambridge, Massachusetts
| | - Andrew D Czaja
- 2 Department of Geology, University of Cincinnati , Cincinnati, Ohio
| | - James Tuggle
- 3 Nanoscale Characterization and Fabrication Laboratory, Institute for Critical Technology and Applied Science , Virginia Tech, Blacksburg, Virginia
| | - Christopher Winkler
- 3 Nanoscale Characterization and Fabrication Laboratory, Institute for Critical Technology and Applied Science , Virginia Tech, Blacksburg, Virginia
| | - Shuhai Xiao
- 4 Department of Geosciences, Virginia Tech , Blacksburg, Virginia
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6
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Miot J, Bernard S, Bourreau M, Guyot F, Kish A. Experimental maturation of Archaea encrusted by Fe-phosphates. Sci Rep 2017; 7:16984. [PMID: 29208997 PMCID: PMC5717249 DOI: 10.1038/s41598-017-17111-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 11/22/2017] [Indexed: 11/15/2022] Open
Abstract
Burial is generally detrimental to the preservation of biological signals. It has often been assumed that (bio)mineral-encrusted microorganisms are more resistant to burial-induced degradation than non-encrusted ones over geological timescales. For the present study, we submitted Sulfolobus acidocaldarius experimentally encrusted by amorphous Fe phosphates to constrained temperature conditions (150 °C) under pressure for 1 to 5 days, thereby simulating burial-induced processes. We document the molecular and mineralogical evolution of these assemblages down to the sub-micrometer scale using X-ray diffraction, scanning and transmission electron microscopies and synchrotron-based X-ray absorption near edge structure spectroscopy at the carbon K-edge. The present results demonstrate that the presence of Fe-phosphates enhances the chemical degradation of microbial organic matter. While Fe-phosphates remained amorphous in abiotic controls, crystalline lipscombite (FeIIxFeIII3-x(PO4)2(OH)3-x) entrapping organic matter formed in the presence of S. acidocaldarius cells. Lipscombite textures (framboidal vs. bipyramidal) appeared only controlled by the initial level of encrustation of the cells, suggesting that the initial organic matter to mineral ratio influences the competition between nucleation and crystal growth. Altogether these results highlight the important interplay between minerals and organic matter during fossilization, which should be taken into account when interpreting the fossil record.
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Affiliation(s)
- J Miot
- IMPMC, Sorbonne Université, MNHN, UPMC, CNRS UMR 7590, 4 pl. Jussieu, 75005, Paris, France.
| | - S Bernard
- IMPMC, Sorbonne Université, MNHN, UPMC, CNRS UMR 7590, 4 pl. Jussieu, 75005, Paris, France
| | - M Bourreau
- MCAM, MNHN, UPMC, CNRS UMR 7245, 63 rue Buffon, 75005, Paris, France
| | - F Guyot
- IMPMC, Sorbonne Université, MNHN, UPMC, CNRS UMR 7590, 4 pl. Jussieu, 75005, Paris, France
| | - A Kish
- MCAM, MNHN, UPMC, CNRS UMR 7245, 63 rue Buffon, 75005, Paris, France
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7
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Alleon J, Bernard S, Le Guillou C, Daval D, Skouri-Panet F, Kuga M, Robert F. Organic molecular heterogeneities can withstand diagenesis. Sci Rep 2017; 7:1508. [PMID: 28473702 PMCID: PMC5431453 DOI: 10.1038/s41598-017-01612-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 03/30/2017] [Indexed: 11/09/2022] Open
Abstract
Reconstructing the original biogeochemistry of organic fossils requires quantifying the extent of the chemical transformations that they underwent during burial-induced maturation processes. Here, we performed laboratory experiments on chemically different organic materials in order to simulate the thermal maturation processes that occur during diagenesis. Starting organic materials were microorganisms and organic aerosols. Scanning transmission X-ray microscopy (STXM) was used to collect X-ray absorption near edge spectroscopy (XANES) data of the organic residues. Results indicate that even after having been submitted to 250 °C and 250 bars for 100 days, the molecular signatures of microorganisms and aerosols remain different in terms of nitrogen-to-carbon atomic ratio and carbon and nitrogen speciation. These observations suggest that burial-induced thermal degradation processes may not completely obliterate the chemical and molecular signatures of organic molecules. In other words, the present study suggests that organic molecular heterogeneities can withstand diagenesis and be recognized in the fossil record.
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Affiliation(s)
- Julien Alleon
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ. Paris 06, IRD UMR 206, 61 rue Buffon, 75005, Paris, France.,Department of Earth Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Sylvain Bernard
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ. Paris 06, IRD UMR 206, 61 rue Buffon, 75005, Paris, France.
| | | | - Damien Daval
- Laboratoire d'Hydrologie et de Géochimie de Strasbourg, Université de Strasbourg/EOST - CNRS UMR 7517, 1 Rue Blessig, 67084, Strasbourg, France
| | - Feriel Skouri-Panet
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ. Paris 06, IRD UMR 206, 61 rue Buffon, 75005, Paris, France
| | - Maïa Kuga
- Department of Earth Sciences, ETH Zürich, 8092, Zürich, Switzerland
| | - François Robert
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ. Paris 06, IRD UMR 206, 61 rue Buffon, 75005, Paris, France
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8
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Alleon J, Bernard S, Le Guillou C, Marin-Carbonne J, Pont S, Beyssac O, McKeegan KD, Robert F. Molecular preservation of 1.88 Ga Gunflint organic microfossils as a function of temperature and mineralogy. Nat Commun 2016; 7:11977. [PMID: 27312070 PMCID: PMC4915024 DOI: 10.1038/ncomms11977] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 05/18/2016] [Indexed: 01/06/2023] Open
Abstract
The significant degradation that fossilized biomolecules may experience during burial makes it challenging to assess the biogenicity of organic microstructures in ancient rocks. Here we investigate the molecular signatures of 1.88 Ga Gunflint organic microfossils as a function of their diagenetic history. Synchrotron-based XANES data collected in situ on individual microfossils, at the submicrometre scale, are compared with data collected on modern microorganisms. Despite diagenetic temperatures of ∼150–170 °C deduced from Raman data, the molecular signatures of some Gunflint organic microfossils have been exceptionally well preserved. Remarkably, amide groups derived from protein compounds can still be detected. We also demonstrate that an additional increase of diagenetic temperature of only 50 °C and the nanoscale association with carbonate minerals have significantly altered the molecular signatures of Gunflint organic microfossils from other localities. Altogether, the present study provides key insights for eventually decoding the earliest fossil record. Thermal diagenesis is generally seen as detrimental to the preservation of organic biosignatures. Using synchrotron-based XANES data, Alleon et al. find preservation of the molecular signatures of organic microfossils from the 1.88 Ga Gunflint cherts.
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Affiliation(s)
- Julien Alleon
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ Paris 06, IRD UMR 206, 61 rue Buffon, 75005 Paris, France
| | - Sylvain Bernard
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ Paris 06, IRD UMR 206, 61 rue Buffon, 75005 Paris, France
| | - Corentin Le Guillou
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ Paris 06, IRD UMR 206, 61 rue Buffon, 75005 Paris, France
| | - Johanna Marin-Carbonne
- Univ Lyon, UJM Saint Etienne, Laboratoire Magma et Volcans, UBP, CNRS, IRD, 23 rue Dr Paul Michelon, 42100 St Etienne, France
| | - Sylvain Pont
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ Paris 06, IRD UMR 206, 61 rue Buffon, 75005 Paris, France
| | - Olivier Beyssac
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ Paris 06, IRD UMR 206, 61 rue Buffon, 75005 Paris, France
| | - Kevin D McKeegan
- Department of Earth, Planetary and Space Sciences, University of California-Los Angeles, 595 Charles Young Drive East, Los Angeles, California 90095-1567, USA
| | - François Robert
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités - CNRS UMR 7590, Muséum National d'Histoire Naturelle, UPMC Univ Paris 06, IRD UMR 206, 61 rue Buffon, 75005 Paris, France
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9
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Delarue F, Rouzaud JN, Derenne S, Bourbin M, Westall F, Kremer B, Sugitani K, Deldicque D, Robert F. The Raman-Derived Carbonization Continuum: A Tool to Select the Best Preserved Molecular Structures in Archean Kerogens. ASTROBIOLOGY 2016; 16:407-417. [PMID: 27186810 PMCID: PMC4900230 DOI: 10.1089/ast.2015.1392] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 12/23/2015] [Indexed: 06/01/2023]
Abstract
UNLABELLED 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, (13)C 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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Affiliation(s)
- Frédéric Delarue
- IMPMC Sorbonne Universités—MNHN, UPMC Univ Paris 06, UMR CNRS 7590, IRD UMR 206, Paris, France
| | | | - Sylvie Derenne
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 7619 METIS, CC 105, Paris, France
| | - Mathilde Bourbin
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 7619 METIS, CC 105, Paris, France
| | - Frances Westall
- Centre de Biophysique Moléculaire, UPR CNRS 4301, Orléans, France
| | - Barbara Kremer
- Institute of Paleobiology, Polish Academy of Sciences, Warszawa, Poland
| | - Kenichiro Sugitani
- Department of Environmental Engineering and Architecture, Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan
| | | | - François Robert
- IMPMC Sorbonne Universités—MNHN, UPMC Univ Paris 06, UMR CNRS 7590, IRD UMR 206, Paris, France
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10
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Bernard S, Benzerara K, Beyssac O, Balan E, Brown GE. Evolution of the macromolecular structure of sporopollenin during thermal degradation. Heliyon 2015; 1:e00034. [PMID: 27123494 PMCID: PMC4832518 DOI: 10.1016/j.heliyon.2015.e00034] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 08/28/2015] [Accepted: 09/25/2015] [Indexed: 11/13/2022] Open
Abstract
Reconstructing the original biogeochemistry of organic microfossils requires quantifying the extent of the chemical transformations they experienced during burial and maturation processes. In the present study, fossilization experiments have been performed using modern sporopollenin chosen as an analogue for the resistant biocompounds possibly constituting the wall of many organic microfossils. Sporopollenin powder has been processed thermally under argon atmosphere at different temperatures (up to 1000 °C) for varying durations (up to 900 min). Solid residues of each experiment have been characterized using infrared, Raman and synchrotron-based XANES spectroscopies. Results indicate that significant defunctionalisation and aromatization affect the molecular structure of sporopollenin with increasing temperature. Two distinct stages of evolution with temperature are observed: in a first stage, sporopollenin experiences dehydrogenation and deoxygenation simultaneously (below 500 °C); in a second stage (above 500 °C) an increasing concentration in aromatic groups and a lateral growth of aromatic layers are observed. With increasing heating duration (up to 900 min) at a constant temperature (360 °C), oxygen is progressively lost and conjugated carbon–carbon chains or domains grow progressively, following a log-linear kinetic behavior. Based on the comparison with natural spores fossilized within metasediments which experienced intense metamorphism, we show that the present experimental simulations may not perfectly mimic natural diagenesis and metamorphism. Yet, performing such laboratory experiments provides key insights on the processes transforming biogenic molecules into molecular fossils.
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Affiliation(s)
- S Bernard
- Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie (IMPMC), Sorbonne Universités - MNHN, UPMC Univ Paris 06, CNRS UMR 7590, IRD UMR 206, 75005 Paris, France
| | - K Benzerara
- Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie (IMPMC), Sorbonne Universités - MNHN, UPMC Univ Paris 06, CNRS UMR 7590, IRD UMR 206, 75005 Paris, France
| | - O Beyssac
- Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie (IMPMC), Sorbonne Universités - MNHN, UPMC Univ Paris 06, CNRS UMR 7590, IRD UMR 206, 75005 Paris, France
| | - E Balan
- Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie (IMPMC), Sorbonne Universités - MNHN, UPMC Univ Paris 06, CNRS UMR 7590, IRD UMR 206, 75005 Paris, France
| | - G E Brown
- Surface & Aqueous Geochemistry Group, Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305-2115, USA; Department of Photon Science and Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
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11
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The 2.1 Ga old Francevillian biota: biogenicity, taphonomy and biodiversity. PLoS One 2014; 9:e99438. [PMID: 24963687 PMCID: PMC4070892 DOI: 10.1371/journal.pone.0099438] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 05/14/2014] [Indexed: 11/20/2022] Open
Abstract
The Paleoproterozoic Era witnessed crucial steps in the evolution of Earth's surface environments following the first appreciable rise of free atmospheric oxygen concentrations ∼2.3 to 2.1 Ga ago, and concomitant shallow ocean oxygenation. While most sedimentary successions deposited during this time interval have experienced thermal overprinting from burial diagenesis and metamorphism, the ca. 2.1 Ga black shales of the Francevillian B Formation (FB2) cropping out in southeastern Gabon have not. The Francevillian Formation contains centimeter-sized structures interpreted as organized and spatially discrete populations of colonial organisms living in an oxygenated marine ecosystem. Here, new material from the FB2 black shales is presented and analyzed to further explore its biogenicity and taphonomy. Our extended record comprises variably sized, shaped, and structured pyritized macrofossils of lobate, elongated, and rod-shaped morphologies as well as abundant non-pyritized disk-shaped macrofossils and organic-walled acritarchs. Combined microtomography, geochemistry, and sedimentary analysis suggest a biota fossilized during early diagenesis. The emergence of this biota follows a rise in atmospheric oxygen, which is consistent with the idea that surface oxygenation allowed the evolution and ecological expansion of complex megascopic life.
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12
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Pang K, Tang Q, Schiffbauer JD, Yao J, Yuan X, Wan B, Chen L, Ou Z, Xiao S. The nature and origin of nucleus-like intracellular inclusions in Paleoproterozoic eukaryote microfossils. GEOBIOLOGY 2013; 11:499-510. [PMID: 24033870 DOI: 10.1111/gbi.12053] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Accepted: 07/23/2013] [Indexed: 05/19/2023]
Abstract
The well-known debate on the nature and origin of intracellular inclusions (ICIs) in silicified microfossils from the early Neoproterozoic Bitter Springs Formation has recently been revived by reports of possible fossilized nuclei in phosphatized animal embryo-like fossils from the Ediacaran Doushantuo Formation of South China. The revisitation of this discussion prompted a critical and comprehensive investigation of ICIs in some of the oldest indisputable eukaryote microfossils-the ornamented acritarchs Dictyosphaera delicata and Shuiyousphaeridium macroreticulatum from the Paleoproterozoic Ruyang Group of North China-using a suite of characterization approaches: scanning electron microscopy (SEM), transmission electron microscopy (TEM), and focused ion beam scanning electron microscopy (FIB-SEM). Although the Ruyang acritarchs must have had nuclei when alive, our data suggest that their ICIs represent neither fossilized nuclei nor taphonomically condensed cytoplasm. We instead propose that these ICIs likely represent biologically contracted and consolidated eukaryotic protoplasts (the combination of the nucleus, surrounding cytoplasm, and plasma membrane). As opposed to degradational contraction of prokaryotic cells within a mucoidal sheath-a model proposed to explain the Bitter Springs ICIs-our model implies that protoplast condensation in the Ruyang acritarchs was an in vivo biologically programmed response to adverse conditions in preparation for encystment. While the discovery of bona fide nuclei in Paleoproterozoic acritarchs would be a substantial landmark in our understanding of eukaryote evolution, the various processes (such as degradational and biological condensation of protoplasts) capable of producing nuclei-mimicking structures require that interpretation of ICIs as fossilized nuclei be based on comprehensive investigations.
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Affiliation(s)
- K Pang
- State Key Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing, China; Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
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13
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Marshall CP, Olcott Marshall A. Raman hyperspectral imaging of microfossils: potential pitfalls. ASTROBIOLOGY 2013; 13:920-31. [PMID: 24088070 PMCID: PMC3807534 DOI: 10.1089/ast.2013.1034] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 08/23/2013] [Indexed: 05/24/2023]
Abstract
Initially, Raman spectroscopy was a specialized technique used by vibrational spectroscopists; however, due to rapid advancements in instrumentation and imaging techniques over the last few decades, Raman spectrometers are widely available at many institutions, allowing Raman spectroscopy to become a widespread analytical tool in mineralogy and other geological sciences. Hyperspectral imaging, in particular, has become popular due to the fact that Raman spectroscopy can quickly delineate crystallographic and compositional differences in 2-D and 3-D at the micron scale. Although this rapid growth of applications to the Earth sciences has provided great insight across the geological sciences, the ease of application as the instruments become increasingly automated combined with nonspecialists using this techique has resulted in the propagation of errors and misunderstandings throughout the field. For example, the literature now includes misassigned vibration modes, inappropriate spectral processing techniques, confocal depth of laser penetration incorrectly estimated into opaque crystalline solids, and a misconstrued understanding of the anisotropic nature of sp² carbons.
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14
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Cosmidis J, Benzerara K, Gheerbrant E, Estève I, Bouya B, Amaghzaz M. Nanometer-scale characterization of exceptionally preserved bacterial fossils in Paleocene phosphorites from Ouled Abdoun (Morocco). GEOBIOLOGY 2013; 11:139-153. [PMID: 23301909 DOI: 10.1111/gbi.12022] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 11/21/2012] [Indexed: 06/01/2023]
Abstract
Micrometer-sized spherical and rod-shaped forms have been reported in many phosphorites and often interpreted as microbes fossilized by apatite, based on their morphologic resemblance with modern bacteria inferred by scanning electron microscopy (SEM) observations. This interpretation supports models involving bacteria in the formation of phosphorites. Here, we studied a phosphatic coprolite of Paleocene age originating from the Ouled Abdoun phosphate basin (Morocco) down to the nanometer-scale using focused ion beam milling, transmission electron microscopy (TEM), and scanning transmission x-ray microscopy (STXM) coupled with x-ray absorption near-edge structure spectroscopy (XANES). The coprolite, exclusively composed of francolite (a carbonate-fluroapatite), is formed by the accumulation of spherical objects, delimited by a thin envelope, and whose apparent diameters are between 0.5 and 3 μm. The envelope of the spheres is composed of a continuous crown dense to electrons, which measures 20-40 nm in thickness. It is surrounded by two thinner layers that are more porous and transparent to electrons and enriched in organic carbon. The observed spherical objects are very similar with bacteria encrusting in hydroxyapatite as observed in laboratory experiments. We suggest that they are Gram-negative bacteria fossilized by francolite, the precipitation of which started within the periplasm of the cells. We discuss the role of bacteria in the fossilization mechanism and propose that they could have played an active role in the formation of francolite. This study shows that ancient phosphorites can contain fossil biological subcellular structures as fine as a bacterial periplasm. Moreover, we demonstrate that while morphological information provided by SEM analyses is valuable, the use of additional nanoscale analyses is a powerful approach to help inferring the biogenicity of biomorphs found in phosphorites. A more systematic use of this approach could considerably improve our knowledge and understanding of the microfossils present in the geological record.
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Affiliation(s)
- J Cosmidis
- Institut de Minéralogie et de Physique des Milieux Condensés, Université Pierre et Marie Curie, CNRS, UMR 7590, Campus Jussieu, F-75005, Paris, France.
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