Title :

Distinguishing cellular from abiotic spheroidal microstructures in the ca. 3.4 Ga Strelley Pool Formation

Author(s) :

Coutant, Maxime [Auteur]
Université de Liège
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Lepot, Kevin [Auteur]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Fadel, Alexandre [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]
Addad, Ahmed [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]
Richard, Élodie [Auteur]
École des hautes études en sciences sociales [EHESS]
Troadec, david [Auteur]
Centrale de Micro Nano Fabrication - IEMN [CMNF - IEMN]
Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 [IEMN]
ventalon, sandra [Auteur]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Sugitani, Kenichiro [Auteur]
Graduate School of Environmental Studies [Nagoya]
Javaux, Emmanuelle [Auteur]
Université de Liège

Journal title :

Geobiology

Pages :

599-622

Publisher :

Wiley

Publication date :

2022-09

ISSN :

1472-4677

English keyword(s) :

Archean
biomorphs
microfossils
spheroids
Strelley Pool Formation

HAL domain(s) :

Sciences de l'ingénieur [physics]

English abstract : [en]

The morphogenesis of most carbonaceous microstructures that resemble microfossils in Archean (4–2.5 Ga old) rocks remains debated. The associated carbonaceous matter may even—in some cases—derive from abiotic organic ...
Show more >The morphogenesis of most carbonaceous microstructures that resemble microfossils in Archean (4–2.5 Ga old) rocks remains debated. The associated carbonaceous matter may even—in some cases—derive from abiotic organic molecules. Mineral growths associated with organic matter migration may mimic microbial cells, some anatomical features, and known microfossils—in particular those with simple spheroid shapes. Here, spheroid microstructures from a chert of the ca. 3.4 Ga Strelley Pool Formation (SPF) of the Pilbara Craton (Western Australia) were imaged and analyzed with a combination of high-resolution in situ techniques. This provides new insights into carbonaceous matter distributions and their relationships with the crystallographic textures of associated quartz. Thus, we describe five new types of spheroids and discuss their morphogenesis. In at least three types of microstructures, wall coalescence argues for migration of carbonaceous matter onto abiotic siliceous spherulites or diffusion in poorly crystalline silica. The nanoparticulate walls of these coalescent structures often cut across multiple quartz crystals, consistent with migration in/on silica prior to quartz recrystallization. Sub-continuous walls lying at quartz boundaries occur in some coalescent vesicles. This weakens the “continuous carbonaceous wall” criterion proposed to support cellular inferences. In contrast, some clustered spheroids display wrinkled sub-continuous double walls, and a large sphere shows a thick sub-continuous wall with pustules and depressions. These features appear consistent with post-mortem cell alteration, although abiotic morphogenesis remains difficult to rule out. We compared these siliceous and carbonaceous microstructures to coalescent pyritic spheroids from the same sample, which likely formed as “colloidal” structures in hydrothermal context. The pyrites display a smaller size and only limited carbonaceous coatings, arguing that they could not have acted as precursors to siliceous spheroids. This study revealed new textural features arguing for abiotic morphogenesis of some Archean spheroids. The absence of these features in distinct types of spheroids leaves open the microfossil hypothesis in the same rock. Distinction of such characteristics could help addressing further the origin of other candidate microfossils. This study calls for similar investigations of metamorphosed microfossiliferous rocks and of the products of in vitro growth of cell-mimicking structures in presence of organics and silica.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Internationale

Popular science :

Non

ANR Project :

Identification moléculaire, minéralogique, morphologique et isotopique des micro- et macrofossiles aux échelles micro et nano.

Collections :

• Laboratoire d'Océanologie et de Géosciences (LOG) - UMR 8187

Source :

Harvested from HAL