Hydrothermal alteration and microfossil artefacts of the 3,465-million-year-old Apex chert

Pinti, Daniele L.; Mineau, Raymond; Clément, Valentin

doi:10.1038/ngeo601

Cited by 73 publications

(47 citation statements)

References 26 publications

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“…We have therefore mapped the context for these candidate microfossils at kilometer to micrometer scales (17)(18)(19), and shown that they came not from a wave-washed beach or stream but from a hydrothermally influenced subsurface vein system, some 100 m below the stratiform Apex chert. Our initial mapping of the microfossils (17,18) argued that they come from within a succession of carbonaceous and metalliferous hydrobreccia fabrics; this has been supported by further research (21,22). The holotypes and paratypes were also examined and the populations mapped, leading to the conclusion that many of the microfossil-like structures are indistinguishable from associated mineral growths (17)(18)(19).…”

Section: The Gunflint Chert: New Analytical Techniquesmentioning

confidence: 99%

“…The holotypes and paratypes were also examined and the populations mapped, leading to the conclusion that many of the microfossil-like structures are indistinguishable from associated mineral growths (17)(18)(19). Separate studies have reported further microfossil-like artifacts from the Apex chert (22,23), but those objects are not carbonaceous in nature, and their direct relevance to the interpretation of the Apex holotypes has been questioned (24).…”

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.

146

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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 Techniquesmentioning

confidence: 99%

Section: The Gunflint Chert: New Analytical Techniquesmentioning

confidence: 99%

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.

146

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“…최근의 연구는 이들이 생물학적으로 생성되었으리라는 의견에 무게를 싣고 있다 (Hofmann et al, 1999;Allwood et al, 2006Allwood et al, , 2009. 스트로 마톨라이트 외에도 약 34억 6천만 년 전 퇴적된 오 스트레일리아의 아펙스 처트(Apex chert)에서 미생물 의 화석으로 생각되는 구조가 발견되었으나 (Schopf, 1994;Schopf et al, 2007), 이 구조가 생물 기원이 아니라는 견해도 존재한다 (Pinti et al, 2009;Brasier et al, 2015). 반면, 약 34억 3천만 년 전 퇴적된 오 스트레일리아의 스트렐리풀층(Strelley Pool Formation) 의 사암에서 발견된 미세 구조는 미생물의 화석일 가 능성이 크다는 분석이 제시되었다 (Brasier et al, 2015).…”

Section: 지질시대에서 나타나는 미생물암unclassified

A Review on Microbialites: a Korean Perspective

Lee¹

2015

The Journal of the Petrological Society of Korea

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Microbialites are defined as rocks formed by microbial organisms. After their first appearance around 3.5 billion years ago, microbialites occur in various depositional environments throughout geological periods. Microbial organisms form microbialites by trapping and binding detrital sediments and/ or precipitating carbonate cements, resulting in formation of various microstructures and mesostructures. Four major types of microbialites are distinguished based on their mesostructures: stromatolite, thrombolite, dendrolite, and leiolite. In the geological records, occurrences of microbialites are influenced by calcium carbonate saturation of seawater and interaction of microbialites with metazoans. Stromatolites mainly flourished during the Precambrian, and diminished as level of atmospheric carbon dioxide declined. On the other hand, thrombolites, mainly formed by calcified microbes, began to flourish from the Neoproterozoic. As metazoans diversified in the Phanerozoic, proportion of the microbialites within sedimentary record declined. Since then, microbialites only occasionally flourished during the Phanerozoic, such as shortly after mass-extinction events. In the Korean Peninsula, microbialites occur in the Neoproterozoic Sangwon System, the Early Paleozoic Joseon Supergroup, and the Cretaceous Gyeongsang Supergroup, which form different shapes according to their age and depositional environments. By performing detailed studies on these Korean microbialites, it is possible to understand how microbes affected geological records and sedimentary environments, as well as their interaction with other organisms.

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“…Other research shows that hydrothermal alterations can also generate filamentous microstructures [61]. [66].…”

Section: Archean Palaeobiologymentioning

confidence: 99%

“…Other interpretations are possible, however. Geologic studies show that microstructure-bearing Archean cherts have commonly experienced one or more episodes of hydrothermal fluid flow [61,62]. Thus, it can be instructive to compare organic textures in Archean cherts with those found in Proterozoic rocks altered by hydrothermal fluids.…”

Section: Archean Palaeobiologymentioning

confidence: 99%