Early Life on Earth: The Ancient Fossil Record

Westall, Francès

doi:10.1007/1-4020-2305-7_12

Cited by 25 publications

(20 citation statements)

References 85 publications

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“…32 Surface mapping confirms a crater of approximately 24 km in diameter formed from the impact of an asteroid or comet which penetrated target rocks comprising thick carbonate sequence (¾1.8 km) underlain by Precambrian granites and gneisses. 34,35 The gypsum specimen studied here ( Fig. Evidence for impact-induced hydrothermal activity is well preserved within the structure including sulfate mineralisation and mobilisation.…”

Section: Halotrophic Colonisation Gypsum (Var Selenite) Haughton Cmentioning

confidence: 76%

Morphological biosignatures from relict fossilised sedimentary geological specimens: a Raman spectroscopic study

Edwards

Villar

Pullan

et al. 2007

J Raman Spectroscopy

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Section: Halotrophic Colonisation Gypsum (Var Selenite) Haughton Cmentioning

confidence: 76%

Morphological biosignatures from relict fossilised sedimentary geological specimens: a Raman spectroscopic study

Edwards

Villar

Pullan

et al. 2007

J Raman Spectroscopy

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“…Geochemical evidence from the Isua Banded Iron Formation (Dymek and Klein, 1988), from radio-and stable isotopes in rocks of the same age (Rosing and Frei, 2003), and 16sRNA evolutionary trees (Pace, 2002), have been taken to imply that it emerged before 3.75 Ga. But soil profiles lacking Fe III and the absence in rocks of the petrified polysaccharide-rich sheaths around fossil cells to be expected of cyanobacteria seem to point to a late or post Archaean age (Westall 2001(Westall , 2003(Westall , 2004. Indeed, Blank (2004) suggests that oxygenic photosynthesis did not emerge until immediately prior to the Great Oxidation Event at ca.…”

Section: The Appearance Of Oxygenic Photosynthesismentioning

confidence: 99%

Geodynamic and metabolic cycles in the Hadean

2005

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Abstract. High-degree melting of hot dry Hadean mantle at ocean ridges and plumes resulted in a crust about 30 km thick, overlain in places by extensive and thick mafic volcanic plateaus. Continental crust, by contrast, was relatively thin and mostly submarine. At constructive and destructive plate boundaries, and above the many mantle plumes, acidic hydrothermal springs at ∼400 • C contributed Fe and other transition elements as well as P and H 2 to the deep ocean made acidulous by dissolved CO 2 and minor HCl derived from volcanoes. Away from ocean ridges, submarine hydrothermal fluids were cool (≤100 • C), alkaline (pH ∼10), highly reduced and also H 2 -rich. Reaction of solvents in this fluid with those in ocean water was catalyzed in a hydrothermal mound, a natural self-restoring flow reactor and fractionation column developed above the alkaline spring. The mound consisted of brucite, Mg-rich clays, ephemeral carbonates, Fe-Ni sulfide and green rust. Acetate and glycine were the main products, some of which were eluted to the ocean. The rest, along with other organic byproducts were retained and concentrated within Fe-Ni sulfide compartments. These compartments, comprising the natural hydrothermal reactor, consisted partly of greigite (Fe 5 NiS 8 ). It was from reactions between organic modules confined within these inorganic compartments that the first prokaryotic organism evolved. These acetogenic precursors to the bacteria diversified and migrated down the mound and into the ocean floor to inaugurate the "deep biosphere". Once there they were protected from cataclysmic heating events caused by large meteoritic impacts. Geodynamic forces led to the eventual obduction of the deep biosphere into the photic zone where, initially protected by a thin veneer of sediment, the use of solar energy was mastered and photosynthesis emerged. The further evolution to oxygenic photosynthesis was effected as catalytic [Mn,Ca] -bearing molecules that otherwise wouldCorrespondence to: N. T. Arndt (arndt@ujf-grenoble.fr) have been interred in minerals such as ranciéite and hollandite in shallow marine manganiferous sediments, were sequestered and invaginated within the cyanobacterial precursor where, energized by light, they could oxidize water. Thus, a chemical sedimentary environment was required both for the emergence of chemosynthesis and of oxygenic photosynthesis, the two innovations that did most to change the nature of our planet.

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“…Pore spaces within mineral aggregates continued to provide housing in which evolutionary innovation could take place (Koonin and Martin 2005). Even today mineral surfaces are colonized by prokaryotes which protect themselves by cooperating in the secretion of biofilm (Westall et al 2001(Westall et al , 2004. Indeed the structures and situations of many microbialites and stromatolites echo that first mound (Fig.…”

Section: Further Use For Mineral Housingmentioning

confidence: 95%

The Alkaline Solution to the Emergence of Life: Energy, Entropy and Early Evolution

Russell

2007

Acta Biotheor

113

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The Earth agglomerates and heats. Convection cells within the planetary interior expedite the cooling process. Volcanoes evolve steam, carbon dioxide, sulfur dioxide and pyrophosphate. An acidulous Hadean ocean condenses from the carbon dioxide atmosphere. Dusts and stratospheric sulfurous smogs absorb a proportion of the Sun's rays. The cooled ocean leaks into the stressed crust and also convects. High temperature acid springs, coupled to magmatic plumes and spreading centers, emit iron, manganese, zinc, cobalt and nickel ions to the ocean. Away from the spreading centers cooler alkaline spring waters emanate from the ocean floor. These bear hydrogen, formate, ammonia, hydrosulfide and minor methane thiol. The thermal potential begins to be dissipated but the chemical potential is dammed. The exhaling alkaline solutions are frustrated in their further attempt to mix thoroughly with their oceanic source by the spontaneous precipitation of biomorphic barriers of colloidal iron compounds and other minerals. It is here we surmise that organic molecules are synthesized, filtered, concentrated and adsorbed, while acetate and methane--separate products of the precursor to the reductive acetyl-coenzyme-A pathway-are exhaled as waste. Reactions in mineral compartments produce acetate, amino acids, and the components of nucleosides. Short peptides, condensed from the simple amino acids, sequester 'ready-made' iron sulfide clusters to form protoferredoxins, and also bind phosphates. Nucleotides are assembled from amino acids, simple phosphates carbon dioxide and ribose phosphate upon nanocrystalline mineral surfaces. The side chains of particular amino acids register to fitting nucleotide triplet clefts. Keyed in, the amino acids are polymerized, through acid-base catalysis, to alpha chains. Peptides, the tenuous outer-most filaments of the nanocrysts, continually peel away from bound RNA. The polymers are concentrated at cooler regions of the mineral compartments through thermophoresis. RNA is reproduced through a convective polymerase chain reaction operating between 40 and 100 degrees C. The coded peptides produce true ferredoxins, the ubiquitous proteins with the longest evolutionary pedigree. They take over the role of catalyst and electron transfer agent from the iron sulfides. Other iron-nickel sulfide clusters, sequestered now by cysteine residues as CO-dehydrogenase and acetyl-coenzyme-A synthase, promote further chemosynthesis and support the hatchery--the electrochemical reactor--from which they sprang. Reactions and interactions fall into step as further pathways are negotiated. This hydrothermal circuitry offers a continuous supply of material and chemical energy, as well as electricity and proticity at a potential appropriate for the onset of life in the dark, a rapidly emerging kinetic structure born to persist, evolve and generate entropy while the sun shines.

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Early Life on Earth: The Ancient Fossil Record

Cited by 25 publications

References 85 publications

Morphological biosignatures from relict fossilised sedimentary geological specimens: a Raman spectroscopic study

Morphological biosignatures from relict fossilised sedimentary geological specimens: a Raman spectroscopic study

Geodynamic and metabolic cycles in the Hadean

The Alkaline Solution to the Emergence of Life: Energy, Entropy and Early Evolution

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