Preprints
https://doi.org/10.5194/egusphere-2022-1116
https://doi.org/10.5194/egusphere-2022-1116
20 Oct 2022
 | 20 Oct 2022

The Volyn biota (Ukraine) – 1.5 Ga old (micro)fossils in 3D-preservation, a spotlight on the ‘boring billion’

Gerhard Franz, Vladimir Khomenko, Peter Lyckberg, Vsevolod Chournousenko, Ulrich Struck, Ulrich Gernert, and Jörg Nissen

Abstract. The Volyn biota, fossilized organisms with a minimum age of 1.5 Ga, were found in cavities in granitic pegmatites from the Korosten pluton, NW Ukrainian shield. Fossilization was due to influx of hydrothermal fluorine-rich waters, which silicified the outermost part of the organisms, thus preserving the 3D morphology. Details of the morphology (investigated by scanning electron microscopy) show that the majority of the specimens is filamentous, of a large variety with diameters ranging from ~10 µm to ~200 µm, thin filaments with typical branching, thick filaments with ball-shaped outgrowths and dented surface. Filaments can be straight or conical, curvilinear or strongly curved, up to mm in length, some with a central channel. Some filaments show indications for segmentation, are grown as sessile organisms onto substrate; others show both intact ends, indicating growth in soft medium or floating in water. Objects with flaky morphology and agglutinating filaments are interpreted as fossil biofilms. Other objects are hollow and show a large variety of forms; spherical objects are scarce. Infrared spectroscopy indicates the presence of chitosan in one filament, electron microprobe analysis of nm-sized inclusions in filaments identified the presence of Bi(Te,S) minerals, and both observations are compatible with the interpretation of filaments as fungi-like organisms. Stable C- and N-isotope data of bulk samples are in the range of -31 to -47 ‰ δ13C/12C, and of +3 to +10 ‰ δ15N/14N, indicating possible methanogenic bacteria as part of the subsurface micro-ecosystem. The Volyn biota show that at 1.5 Ga fungi-like organisms lived in the continental deep biosphere, where complex forms of life existed, well above the microscopic level.

Gerhard Franz et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-1116', Anonymous Referee #1, 30 Nov 2022
    • AC1: 'Reply on RC1', Gerhard Franz, 07 Feb 2023
  • RC2: 'Comment on egusphere-2022-1116', Anonymous Referee #2, 26 Jan 2023
    • AC2: 'Reply on RC2', Gerhard Franz, 07 Feb 2023
  • RC3: 'Comment on egusphere-2022-1116', Anonymous Referee #3, 27 Jan 2023
    • AC3: 'Reply on RC3', Gerhard Franz, 07 Feb 2023

Gerhard Franz et al.

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Short summary
This research describes the occurrence of Precambrian fossils, with an exceptionally well preserved morphology in 3D. These microfossils reach a size of mm (possibly up to cm) and thus indicate the presence of multicellular organisms. Furthermore, these fossils lived in a depth of several hundred meters and thus provide good evidence for a continental the deep biosphere, from a time generally considered as the 'boring billion'.