Structural characterization by Raman hyperspectral mapping of organic carbon in the 3.46 billion-year-old Apex chert, Western Australia

Sforna, Marie-Catherine; Zuilen, Mark A. van; Philippot, Pascal

doi:10.1016/j.gca.2013.09.031

Cited by 109 publications

(87 citation statements)

References 65 publications

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“…Our nonbiological formation model, consistent with multiple fluid flow events (30,31), is: (i) hydration of mica flakes (abundant in the country rock) during widespread hydrothermal activity resulting in vermiculite-like phyllosilicate formation; (ii) continued heating plus rapid expulsion of water from phyllosilicate crystal lattices, causing exfoliation (i.e., accordion-like expansion at right angles to the cleavage plane), and creating the initial vermiform morphological expression of microfossil-like artifacts; and (iii) adsorption of later hydrocarbons (and locally additional iron) onto the vermiculite, mimicking cell walls. We note that exfoliated vermiculite has high adsorption capacity resulting from the strong capillary action of slit-like pores between plate-like grains (27), encouraging its use for cleaning up oil spills (27,32).…”

Section: The Gunflint Chert: New Analytical Techniquessupporting

confidence: 76%

“…More importantly, a biogenic carbon source can create microfossil-like artifacts when redistributed from either adjacent units or from biological communities within the system. Recent studies have shown that there are multiple populations of carbonaceous material within the Apex chert (29)(30)(31), each with different thermal alteration histories, suggesting repeated episodes of carbon introduction and/or redistribution within this unit. This has been interpreted to result from multiple pulses of hydrothermal and metamorphic activity, fluid flow, and weathering (30,31), providing ideal conditions for the creation of carbonaceous microfossil-like artifacts.…”

Section: The Gunflint Chert: New Analytical Techniquesmentioning

confidence: 99%

“…Recent studies have shown that there are multiple populations of carbonaceous material within the Apex chert (29)(30)(31), each with different thermal alteration histories, suggesting repeated episodes of carbon introduction and/or redistribution within this unit. This has been interpreted to result from multiple pulses of hydrothermal and metamorphic activity, fluid flow, and weathering (30,31), providing ideal conditions for the creation of carbonaceous microfossil-like artifacts. Of particular note is the discovery of a late-stage carbon population, associated with hematite at the original microfossil site (31), that exhibits a very similar Raman spectrum to those previously illustrated (24,25) for the microfossil holotypes.…”

Section: The Gunflint Chert: New Analytical Techniquesmentioning

confidence: 99%

“…This has been interpreted to result from multiple pulses of hydrothermal and metamorphic activity, fluid flow, and weathering (30,31), providing ideal conditions for the creation of carbonaceous microfossil-like artifacts. Of particular note is the discovery of a late-stage carbon population, associated with hematite at the original microfossil site (31), that exhibits a very similar Raman spectrum to those previously illustrated (24,25) for the microfossil holotypes.…”

Section: The Gunflint Chert: New Analytical Techniquesmentioning

confidence: 99%

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Changing the picture of Earth's earliest fossils (3.5–1.9 Ga) with new approaches and new discoveries

Brasier

Antcliffe

Saunders

et al. 2015

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

145

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New analytical approaches and discoveries are demanding fresh thinking about the early fossil record. The 1.88-Ga Gunflint chert provides an important benchmark for the analysis of early fossil preservation. High-resolution analysis of Gunflintia shows that microtaphonomy can help to resolve long-standing paleobiological questions. Novel 3D nanoscale reconstructions of the most ancient complex fossil Eosphaera reveal features hitherto unmatched in any crown-group microbe. While Eosphaera may preserve a symbiotic consortium, a stronger conclusion is that multicellular morphospace was differently occupied in the Paleoproterozoic. The 3.46-Ga Apex chert provides a test bed for claims of biogenicity of cell-like structures. Mapping plus focused ion beam milling combined with transmission electron microscopy data demonstrate that microfossil-like taxa, including species of Archaeoscillatoriopsis and Primaevifilum, are pseudofossils formed from vermiform phyllosilicate grains during hydrothermal alteration events. The 3.43-Ga Strelley Pool Formation shows that plausible early fossil candidates are turning up in unexpected environmental settings. Our data reveal how cellular clusters of unexpectedly large coccoids and tubular sheath-like envelopes were trapped between sand grains and entombed within coatings of dripstone beach-rock silica cement. These fossils come from Earth’s earliest known intertidal to supratidal shoreline deposit, accumulated under aerated but oxygen poor conditions.

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Section: The Gunflint Chert: New Analytical Techniquessupporting

confidence: 76%

Section: The Gunflint Chert: New Analytical Techniquesmentioning

confidence: 99%

Section: The Gunflint Chert: New Analytical Techniquesmentioning

confidence: 99%

Section: The Gunflint Chert: New Analytical Techniquesmentioning

confidence: 99%

See 2 more Smart Citations

Changing the picture of Earth's earliest fossils (3.5–1.9 Ga) with new approaches and new discoveries

Brasier

Antcliffe

Saunders

et al. 2015

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

145

View full text Add to dashboard Cite

show abstract

“…At least some Archean microstructures could be nonbiological features that reflect hydrothermal alteration and associated migration of organic carbon (e.g., Brasier et al 2005;Sforna et al 2014). Migrating organics can be adsorbed onto mineral grains, and this is clearly evident in early Archean cherts (Knoll 2012); spheroidal and solid filamentous structures can also selforganize during metamorphism.…”

Section: Problems Of Archean Paleobiologymentioning

confidence: 99%

Paleobiological Perspectives on Early Microbial Evolution

Knoll

2015

Cold Spring Harb Perspect Biol

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Microfossils, stromatolites, and chemical biosignatures indicate that Earth became a biological planet more than 3.5 billion years ago, making most of life's history microbial. Proterozoic rocks preserve a rich record of cyanobacteria, including derived forms that differentiate multiple cell types. Stromatolites, in turn, show that microbial communities covered the seafloor from tidal flats to the base of the photic zone. The Archean record is more challenging to interpret, particularly on the question of cyanobacterial antiquity, which remains to be resolved. In the late Neoproterozoic Era, increasing oxygen and radiating eukaryotes altered the biosphere, with planktonic algae gaining ecological prominence in the water column, whereas seaweeds and, eventually, animals spread across shallow seafloors. From a microbial perspective, however, animals, algae, and, later, plants simply provided new opportunities for diversification, and, to this day, microbial metabolisms remain the only essential components of biogeochemical cycles.

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Revealing the biotic origin of silicified Precambrian carbonaceous microstructures using Raman spectroscopic mapping, a potential method for the detection of microfossils on Mars

Foucher

Ammar

Westall

2015

J Raman Spectroscopy

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International audienceDemonstrating the biogenicity of carbonaceous microfossils can be relatively difficult because of their small size and simple shape, and to the degradation of the associated organic molecules with time. For Precambrian fossils, it generally requires the use of several techniques to study the shape and the composition of the structure itself, as well as its mineral environment. The ability to identify both organic matter and minerals using Raman spectroscopy makes it a key technique in the field of micropaleontology. Raman instruments are also being developed for the upcoming missions to Mars, ExoMars and Mars 2020, both dedicated to the search for past or present traces of life. However, demonstrating the biotic origin of carbonaceous matter in geological materials using this technique is controversial. Here, we show that Raman mapping instead of single spot analysis can detect variations in the composition of carbonaceous matter associated with fossilized microbes in the 800-Ma-old microfossils from the Draken Formation, Svalbard. This discovery is of great interest because it permits assessment of the biotic origin of a fossilized carbonaceous structure. Raman mapping could thus be of crucial importance in the near future for detecting potential fossilized microbial remains in Martian rocks

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Structural characterization by Raman hyperspectral mapping of organic carbon in the 3.46 billion-year-old Apex chert, Western Australia

Cited by 109 publications

References 65 publications

Changing the picture of Earth's earliest fossils (3.5–1.9 Ga) with new approaches and new discoveries

Changing the picture of Earth's earliest fossils (3.5–1.9 Ga) with new approaches and new discoveries

Paleobiological Perspectives on Early Microbial Evolution

Revealing the biotic origin of silicified Precambrian carbonaceous microstructures using Raman spectroscopic mapping, a potential method for the detection of microfossils on Mars

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