Framboidal structures in Earth rocks and in astromaterials

Astafieva, M. M.; Rozanov, A. Yu.; Hoover, Richard B.

doi:10.1117/12.513434

Cited by 7 publications

(7 citation statements)

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“…34,35 Other possible biominerals in meteorites include the iron-rich framboids with precise monodisperse crystallites as were previously described. [36][37][38] Although these results are suggestive, whether these spherical or ellipsoidal forms are biogenic or merely abiotic mimics remains unresolved.…”

Section: Non-filamentous Cyanobacteriamentioning

confidence: 81%

Mineralized remains of morphotypes of filamentous cyanobacteria in carbonaceous meteorites

Hoover

2005

Astrobiology and Planetary Missions

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The quest for conclusive evidence of microfossils in meteorites has been elusive. Abiotic microstructures, mineral grains, and even coating artifacts may mimic unicellular bacteria, archaea and nanobacteria with simple spherical or rod morphologies (i.e., cocci, diplococci, bacilli, etc.). This is not the case for the larger and more complex microorganisms, colonies and microbial consortia and ecosystems. Microfossils of algae, cyanobacteria, and cyanobacterial and microbial mats have been recognized and described from many of the most ancient rocks on Earth. The filamentous cyanobacteria and sulphur-bacteria have very distinctive size ranges, complex and recognizable morphologies and visibly differentiated cellular microstructures. The taphonomic modes of fossilization and the life habits and processes of these microorganisms often result in distinctive chemical biosignatures associated with carbonization, silicification, calcification, phosphatization and metal-binding properties of their cell-walls, trichomes, sheaths and extracellular polymeric substances (EPS). Valid biogenicity is provided by the combination of a suite of known biogenic elements (that differ from the meteorite matrix) found in direct association with recognizable and distinct biological features and microstructures (e.g., uniseriate or multiseriate filaments, trichomes, sheaths and cells of proper size/size range); specialized cells (e.g., basal or apical cells, hormogonia, akinetes, and heterocysts); and evidence of growth characteristics (e.g., spiral filaments, robust or thin sheaths, laminated sheaths, true or false branching of trichomes, tapered or uniform filaments) and evidence of locomotion (e.g. emergent cells and trichomes, coiling hormogonia, and hollow or flattened and twisted sheaths).Since 1997 we have conducted Environmental and Field Emission Scanning Electron Microscopy (ESEM and FESEM) studies of freshly fractured interior surfaces of carbonaceous meteorites, terrestrial rocks, living, cryopreserved and fossilized extremophiles and cyanobacteria. These studies have resulted in the detection of mineralized remains of morphotypes of filamentous cyanobacteria, mats and consortia in many carbonaceous meteorites. These well-preserved and embedded microfossils are consistent with the size, morphology and ultramicrostructure of filamentous trichomic prokaryotes and degraded remains of microfibrils of cyanobacterial sheaths. EDAX elemental studies reveal that the forms in the meteorites often have highly carbonized sheaths in close association with permineralized filaments, trichomes, and microbial cells. The eextensive protocols and methodologies that have been developed to protect the samples from contamination and to distinguish recent contaminants from indigenous microfossils are described recent bio-contaminants. Ratios of critical bioelements (C:O, C:N, C:P, and C:S) reveal dramatic differences between microfossils in Earth rocks and meteorites and in the cells, filaments, trichomes, and hormogonia of recently living cyanob...

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Section: Non-filamentous Cyanobacteriamentioning

confidence: 81%

Mineralized remains of morphotypes of filamentous cyanobacteria in carbonaceous meteorites

Hoover

2005

Astrobiology and Planetary Missions

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“…The framboids are typically spherical (diameters 2-5 µm) with uniform sized (0.2 to 0.5 µm diameter) crystallites of magnetite, pyrite or occasionally elemental iron. 44 Clearly, these framboids may have been formed by biological process but it is also possible that they are the result of abiotic processes in the protosolar nebula or on the meteorite parent body. Figure 6.a.…”

Section: Framboids In Orgueilmentioning

confidence: 99%

“…[34][35][36][37] However, framboids are also frequently encountered in soils, black carbonaceous shales, and cold-seep carbonates on Earth where it is thought that their formation is the result of the biological activity of magnetotactic bacteria or anaerobic sulfate-reducing bacteria and other microorganisms. [38][39][40][41][42][43][44] Consequently the Orgueil framboids must also be considered as being of indeterminate biogenicity. However, it is interesting that the biogenically produced pyrite and magnetite framboids found in recent silts are characterized by the presence of a semitransparent organic envelope.…”

Section: Framboids In Orgueilmentioning

confidence: 99%

Fossils of Prokaryotic microorganisms in the Orgueil meteorite

Hoover

2006

SPIE Proceedings

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The Orgueil CI1 meteorite, which fell in southern France on the evening of May 14, 1864, has been one of the most extensively studied of all known carbonaceous meteorites. Environmental and Field Emission Scanning Electron Microscopy (ESEM and FESEM) studies of freshly fractured interior surfaces of the Orgueil meteorite have resulted in the detection of the fossilized remains of a large and diverse population of filamentous prokaryotic microorganisms. The taphonomy and the modes of the preservation of these remains are diverse. Some of the remains exhibit carbonization of a hollow sheath and in other cases the remains are permineralized with watersoluble evaporite minerals, such as magnesium sulfate or ammonium salts. Images and EDS spectral data are provided documenting a variety of Orgueil microstructures: abiotic evaporite minerals; pre-solar grains; framboids, ovoids and fluorine-rich filaments of indeterminate biogenicity. These results provide information regarding the size, size range, morphologies and chemical compositions of abiotic microstructures found in native cryptohalite and crystalline and fibrous epsomites from Poison Lake, Washington, USA and Catalayud, Zaragoza, Aragon, Spain.High resolution ESEM and FESEM secondary and backscattered electron Images and Energy Dispersive X-ray Spectroscopy (EDS) data will also be presented of recognizable filamentous cyanobacteria and other prokaryotic microfossils. Many of the microfossils found embedded in the meteorite rock matrix are consistent in size and microstructure with known genera and species of filamentous cyanobacteria. Many of these forms can be recognized as morphotypes of cyanobacteria belonging to the Order Oscillatoriaceae. These large, complex microstructures are clearly distinguishable from the abiotic minerals examined -cryptohalite and fibrous epsomites. Many of the wellpreserved filamentous forms in the Orgueil meteorite are embedded in the rock matrix and exhibit identifiable biological characteristics and EDS elemental compositions that clearly differentiate them from abiotic microstructures. They exhibit branched and unbranched filaments; uniseriate and multiseriate ensheathed trichomes with specialized cells and structures for reproduction (e.g. hormogonia and akinetes) and nitrogen fixation (heterocysts). The meteorite forms also show evidence of motility (emergent hormogonia and hollow, coiled empty sheaths) and they are often found in mats, consortia and microbial assemblages that are consistent with the known associations and ecologies of modern genera and species of cyanobacteria. Smaller filaments, consistent with the phototrophic filamentous prokaryotes typically present in anoxic layers associated with modern cyanobacterial mats, have also been found in the Orgueil meteorite.

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“…The samples returned from the near-Earth from asteroid (101955) Bennu and the Mons Rümker dome may provide new insights into the nature and origin of these exotic ungrouped meteorites. The presence of ancient microfossils in Orgueil, Murchison, Polonnaruwa/Aralaganwila and other carbonaceous chondrites [33][34][35][36][37][38][39][40][41][42] may also hold vital clues to the Origin of Life on Earth as well as to the distribution of Biospheres throughout the Cosmos.…”

Section: Ammsmsid0006266(1)2020mentioning

confidence: 99%

“…These studies resulted in the discovery [33,34] of similar microfossils of filamentous cyanobacteria and other microbial remains embedded in rock matrix of the meteorite samples from different sources in Russia and the United States. Subsequently, collaborative studies showed a great diversity of wellpreserved, recognizable microfossils of filamentous cyanobacteria, diatoms, prasinophytes and other microalgae in Murchison (CM2), Orgueil (CI1) and several other groups of carbonaceous chondrites [35][36][37][38][39][40]. Energy dispersive X-ray Spectroscopy revealed that these clearly biological remains exhibited ratios of essential biogenic element consistent with ancient permineralized or carbonized microfossils rather than recent terrestrial bio-contaminants [41].…”

Section: Introductionmentioning

confidence: 99%

Epithermal Neutron Activation Analysis of Carbonaceous Chondrites and the Polonnaruwa/Aralaganwila Stones

Frontasyeva²,

Павлов

2020

AMMS

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The results of multi-element epithermal neutron activation analysis of extraterrestrial materials-Carbonaceous Chondrites and the Polonnaruwa/Aralaganwila Stones-are reported. A total of 41 elements were determined at the reactor IBR-2 of the Joint Institute for Nuclear Research in Dubna, Russian Federation. Special emphasis is made on anomalous levels in the Polonnaruwa/Aralaganwila stones of heat-producing elements (HPE's) Potassium (K), Thorium and Uranium and the Rare Earth Elements (REE), as compared with theTh, U, and KREEP component of Lunar basalts and the Orgueil, Murchison, Sutter's Mill and NWA carbonaceous chondrites.

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Framboidal structures in Earth rocks and in astromaterials

Cited by 7 publications

References 0 publications

Mineralized remains of morphotypes of filamentous cyanobacteria in carbonaceous meteorites

Mineralized remains of morphotypes of filamentous cyanobacteria in carbonaceous meteorites

Fossils of Prokaryotic microorganisms in the Orgueil meteorite

Epithermal Neutron Activation Analysis of Carbonaceous Chondrites and the Polonnaruwa/Aralaganwila Stones

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