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Carbon Isotopic Signatures of Individual Archean Microfossils(?) from Western Australia
International Geology Review
Abstract
New types of carbonaceous filamentous microstructures have been identified in silica veins at two new localities in the ∼3.5 Ga North Pole area of Western Australia. Their carbon isotopic compositions were measured in situ by secondary-ion mass spectrometry. The carbonaceous filaments are ∼1μm wide, 10 to 100 μm long, and are permineralized in a fine-grained (∼1 μm) silica matrix. They are morphologically divided into three types (i.e., spiral, threadlike, and branched filaments). Their sizes and morphologies resemble modern and previously reported fossil bacteria. These similarities and their complex three-dimensional geometry suggest that they may represent morphologically preserved fossil bacteria. δC values of the carbonaceous filaments range from −42 to −32‰, which strongly suggest that they are composed of biologically fixed organic compounds, possibly via the reductive acetyl-CoA pathway or the Calvin cycle. This is consistent with the hypothesis that autotrophs already existed on the Archean Earth.
... μCT scanning is nondestructive and shows internal structure through X-ray density contrast, enabling visualization and measurements of specimens deeper than surface level without the loss of material. Here, we used μCT scanning to image samples from the 3.48 Ga Dresser Formation of Western Australia, a rock succession that has previously been described (Buick & Dunlop, 1990;Walter et al., 1980;and many others) and that contains diverse evidence for microbial life, including well-known examples of early stromatolites and microfossils (e.g., Ueno et al., 2001;Van Kranendonk et al., 2008). It also includes sequences containing MISS , from which the samples described herein were obtained. ...
... Past studies have also measured the isotopic composition of organic carbon, sulfate, and sulfide in the Dresser Fm., including at this locality (Baumgartner et al., 2020;Flannery et al., 2018;Golding et al., 2011;Morag et al., 2016;Philippot et al., 2007Philippot et al., , 2012Shen et al., 2001Shen et al., , 2009Ueno et al., 2001Ueno et al., , 2008Wacey et al., 2015). ...
... Westall et al. (2001),Ueno et al. (2001Ueno et al. ( , 2004Ueno et al. ( , 2008,Philippot et al. (2007Philippot et al. ( , 2012,Wacey et al. (2010Wacey et al. ( , 2014,Golding et al. (2011),Bontognali et al. (2012), andRoerdink et al. (2012) were previously compiled byHavig et al. (2017); additional data were compiled fromWacey et al., 2015;Morag et al. (2016),Flannery et al. (2018), andBaumgartner et al. (2020). Isotopic data are available in a supplemental file.original ...
... The carbonaceous matter [typically <0.2 weight % (wt%) total organic carbon] is dispersed in black chert, including in vertical veins several kilometers deep and several meters wide, which transect underlying basalts and terminate in a chert-barite unit, commonly forming synsedimentary barite mounds up to 15 m high and 50 m wide (3). The vertical vein-mound systems are interpreted to represent fossilized fluid conduits of hydrothermal vent systems (3)(4)(5)(6)(7). ...
... The carbonaceous black cherts and intercalated sedimentary rocks contain purported microfossils and stromatolitic structures (8)(9)(10)(11)(12)(13)(14), as well as sulfur and carbon isotopic signatures (4,5,(15)(16)(17), consistent with the establishment of life 3.5 Ga ago. However, the robustness of the various biosignatures has been questioned, including the biological origin of the 13 C-depleted carbon (between −38.1 and −29.4‰) (5), which theoretically could have been produced by one or more abiotic processes (18,19). ...
... The widespread distribution of reduced carbon in veins originating in basaltic and komatiitic lavas deep below the chert-barite unit points to a potential contribution from abiotic hydrocarbons (Fig. 9). Although the 13 C-depleted isotopic composition of carbonaceous matter in black chert from the North Pole area (δ 13 C, −38.1 to −29.4‰) (4,5,20) is consistent with biological fractionation, laboratory experiments and analysis of Martian meteorites show that abiotic processes can also produce reduced organic compounds depleted in 13 C (19,56,57). While more work is needed to investigate abiotic carbon synthesis and C isotope fractionation (19), the presence of 13 C-depleted carbonaceous matter, particularly in Earth's oldest rocks, does not uniquely indicate a biological origin. ...
Carbon is the key element of life, and its origin in ancient sedimentary rocks is central to questions about the emergence and early evolution of life. The oldest well-preserved carbon occurs with fossil-like structures in 3.5-billion-year-old black chert. The carbonaceous matter, which is associated with hydrothermal chert-barite vent systems originating in underlying basaltic-komatiitic lavas, is thought to be derived from microbial life. Here, we show that 3.5-billion-year-old black chert vein systems from the Pilbara Craton, Australia contain abundant residues of migrated organic carbon. Using younger analogs, we argue that the black cherts formed during precipitation from silica-rich, carbon-bearing hydrothermal fluids in vein systems and vent-proximal seafloor sediments. Given the volcanic setting and lack of organic-rich sediments, we speculate that the vent-mound systems contain carbon derived from rock-powered organic synthesis in the underlying mafic-ultramafic lavas, providing a glimpse of a prebiotic world awash in terrestrial organic compounds.
... The underlying basalts are transected by numerous black chert veins that terminate in the chert-barite unit. The black chert veins and associated black chert beds contain carbonaceous structures that have been compared to fossilized microbes (28)(29)(30), although their biological affinity is unclear (31)(32)(33). ...
Paleoarchean jaspilites are used to track ancient ocean chemistry and photoautotrophy because they contain hematite interpreted to have formed following biological oxidation of vent-derived Fe(II) and seawater P-scavenging. However, recent studies have triggered debate about ancient seawater Fe and P deposition. Here, we report greenalite and fluorapatite (FAP) nanoparticles in the oldest, well-preserved jaspilites from the ~3.5-billion-year Dresser Formation, Pilbara Craton, Australia. We argue that both phases are vent plume particles, whereas coexisting hematite is linked to secondary oxidation. Geochemical modeling predicts that hydrothermal alteration of seafloor basalts by anoxic, sulfate-free seawater releases Fe(II) and P that simultaneously precipitate as greenalite and FAP upon venting. The formation, transport, and preservation of FAP nanoparticles indicate that seawater P concentrations were ≥1 to 2 orders of magnitude higher than in modern deepwater. We speculate that Archean seafloor vents were nanoparticle “factories” that, on prebiotic Earth, produced countless Fe(II)- and P-rich templates available for catalysis and biosynthesis.
... They also preserve cyclic concentrations of transition metals and metalloids that are known to bind to OM and are indicative of biochemical processes (Baumgartner et al., 2020c). Putative carbonaceous microfossils, many showing δ 13 C OM values indicative of biological fractionation, are observed within both bedded chert and hydrothermal chert veins (Dunlop et al., 1978;Ueno et al., 2001a;Ueno et al., 2001b;Ueno et al., 2004;Glikson et al., 2008;Morag et al., 2016). Methane in fluid inclusions from syn-depositional hydrothermal veins is used to argue for methanogenesis (Ueno et al., 2006). ...
... Microanalytical techniquesincluding Raman spectroscopy and Secondary Ion Mass Spectroscopyhave shed light on relationships to microtextural and mineralogical features, as is required for discerning between endogenous and exogenous origins of OM. The importance of microanalytical approaches is well demonstrated for the hydrothermally influenced fossiliferous strata from the ~3.43 billion-years-old (Ga) Strelley Pool Formation and ~3.48 Ga Dresser Formation, both representing key targets for studying primordial life as they have aided to documenting syngeneities between endogenous OM, microtextures that are typical of microbial mediation (i.e., stromatolites and microbially induced sedimentary structures), organomineralization, and also probable microfossils (Ueno et al., 2001;Allwood et al., 2006a, Many of the uncertainties concerning the origins of Paleoarchean OM stem from the loss of original organic molecular characteristics due to thermal maturation beyond the catagenesis windowin accordance with OM from sedimentary petroleum systems, hereafter referred to heating to temperatures of ≳150 ˚C for overmature OM, opposed to ~100-150 ˚C and ≲100 ˚C for mature and immature OM, respectively (Tissot and Welte, 1984;Hunt, 1994;Horsfield and Rullkotter, 1994). The thermal maturity of ancient OM rarely reflects original processes, such as (near-) syndepositional hydrothermal activity. ...
Fossil organic matter (OM) in Paleoarchean rocks is an invaluable tracer of ancient life, yet it is often contentious due to low preservation potentials of its original organic molecular characteristics under generally high metamorphic grades. This study reports on exceptionally preserved OM within black smoker-type sulfide mineralizations from the 3.24 billion-years-old Sulphur Springs volcanic-hosted massive sulfide deposit, East Pilbara Terrane, northwestern Australia. Fine scale mineralogical and organic molecular variations – documented by SEM and TEM techniques, Raman and FTIR Spectroscopy, as well as ToF-SIMS analysis – trace the formation of millimetre-scale pyritic hydrothermal orifices. Overmature OM (≳200–250 °C) enriched in aromatic hydrocarbons occurs within earliest formed colloform-banded pyrite that could have precipitated at high temperature upon mixing of hot hydrothermal fluids with cold seawater. In contrast, mature OM (within the catagenesis window; ~100–150 °C) with lower proportions of aromatic hydrocarbons occasionally occurs alongside pyrite within barite near the inner paleofluid conduits of the hydrothermal orifices. A deposition of this OM generation from cooler fluids enriched in sulfate during waning hydrothermal activity is corroborated by its association with original mineralogy, particularly the occurrence of isolated nanoinclusions of OM within hydrothermal barite away from grain boundaries or fissures and cracks, which renders impossible an origin from post-depositional hydrocarbon migration. When compared to the overmature OM within colloform-banded pyrite, the better-preserved inner OM not only contains less abundant, smaller, and less ordered aromatic hydrocarbons, but also higher amounts of aliphatic molecules with longer chain lengths and higher proportions of carbonyl and amide functional groups. Although the latter characteristics are consistent with contributions by microbial biomass, abiotic origins are equally plausible because hydrothermal processes can produce OM with similar organic molecular attributes. Irrespective of these uncertainties on the ultimate sourcing of OM, common intergrowths of the cooler OM with nanoscopic iron oxides – hematite and lesser magnetite – hint at its hydrothermal deposition from colloidal particles that have been stabilized by iron-organic complexation. Further research is required to ascertain the significance of this process for the hydrothermal cycling and release of organic carbons and bound iron into the Paleoarchean oceans. Collectively, our results show that ancient marine hydrothermal systems can preserve OM with differing degrees of thermal degradation, which allows for insights into its sourcing, cycling, and deposition.
... The results of the shrimp shell characterization are show in Table 1. forming an extracellular matrix [17]. The increasing number of fibroblast cells, the more collagen produced will also increase. ...
p>Modern dressing techniques as open wound dressings are still effective and suitable for use, especially for people with open wounds such as ulcers, but they still have disadvantages, such as the high prices and need for other antibiotics to prevent inflammation. Previous studies reported an increase in the number of antibiotic resistance, which sparked the idea of producing new dressing materials that have strong antimicrobial and biocompatible properties. The material suitable for the idea of a wound dressing is chitosan biofilm because it has strong antibacterial properties and has a similar structure to the skin tissue. This study aims to produce chitosan biofilm using the deacetylation method using a strong base. The physicochemical characterization results of biofilms showed a deacetylation degree of 87.13 with a voltage of 1.15 ± 0.00 and a polycationic group of biofilms that appeared at a wavenumber of 2.1714 ± 0.0000 nm. From the measurement of the antibacterial power of chitosan biofilm against skin surface bacteria, the inhibition zone diameter was 18.93 ± 0.12; 19.50 ± 0.17; 20.20 ± 0.23; 20.13 ± 0.03 and 22.53 ± 0.09 against S. aureus, S. epidermidis, P. aeruginosa, E. colli, Bacillus sp. Overall, it can be concluded that biofilm chitosan has the opportunity to be applied as a dressing in wound care.</p
Paleoarchean carbonates in the Pilbara Craton (Western Australia) are important archives for early life and environment on early Earth. Amongst others, carbonates occur in interstitial spaces of ca. 3.5–3.4 Ga pillow basalts (North Star-, Mount Ada-, Apex-, and Euro Basalt, Dresser Formation) and associated with bedded deposits (Dresser- and Strelley Pool Formation, Euro Basalt). This study aims to understand the formation and geobiological significance of those early Archean carbonates by investigating their temporal-spatial distribution, petrography, mineralogy, and geochemistry (e.g., trace elemental compositions, δ13C, δ18O). Three carbonate factories are recognized: (i) an oceanic crust factory, (ii) an organo-carbonate factory, and (iii) a microbial carbonate factory. The oceanic crust factory is characterized by carbonates formed in interspaces between pillowed basalts (“interstitial carbonates”). These carbonates precipitated inorganically on and within the basaltic oceanic crust from CO2-enriched seawater and seawater-derived alkaline hydrothermal fluids. The organo-carbonate factory is characterized by carbonate precipitates that are spatially associated with organic matter. The close association with organic matter suggests that the carbonates formed taphonomically via organo-mineralization, that is, linked to organic macromolecules (either biotic or abiotic) which provided nucleation sites for carbonate crystal growth. Organo-carbonate associations occur in a wide variety of hydrothermally influenced settings, ranging from shallow marine environments to terrestrial hydrothermal ponds. The microbial carbonate factory includes carbonate precipitates formed through mineralization of extracellular polymeric substances (EPS) associated with microbial mats and biofilms. It is commonly linked to shallow subaquatic environments, where (anoxygenic) photoautotrophs might have been involved in carbonate formation. In case of all three carbonates factories, hydrothermal fluids seem to play a key-role in the formation and preservation of mineral precipitates. For instance, alkaline earth metals and organic materials delivered by fluids may promote carbonate precipitation, whilst soluble silica in the fluids drives early chert formation, delicately preserving authigenic carbonate precipitates and associated features. Regardless of the formation pathway, Paleoarchean carbonates might have been major carbon sinks on the early Earth, modulating the carbon cycle and, hence, climate variability.
The 3530–3427 Ma Warrawoona Group is the oldest of the three groups that make up the Pilbara Supergroup. This 3530–3235 Ma supergroup comprises the Paleoarchean greenstone succession of the East Pilbara Terrane and is preserved in 20 greenstone belts. The group was erupted across the entire area of the 3800–3530 Ma Pilbara crust (Chap. 2), and its thickness varies between 10 and 15 km. Variations are partly due to local erosional unconformities that were formed from 3460 Ma onwards when granite–greenstone domes of the terrane began to rise at different rates. Apart from thin sedimentary units deposited between 3490 and 3474 Ma and between 3459 and 3450 Ma, the Warrawoona Group is volcanic. The succession is composed of successive ultramafic–mafic–felsic volcanic cycles in which felsic volcanism was contemporaneous with intrusion of tonalite–trondhjemite–granodiorite (TTG). Field exposures reveal that many of the TTG intrusions were subvolcanic to the felsic volcanic formations. The East Pilbara Terrane is now exposed across 40,000 km2 of the northeast section of the Pilbara Craton, with concealed parts estimated to occupy an additional 60,000 km2. With an interpreted total volume of volcanic rocks exceeding 1,000,000 km3, the Warrawoona Group easily meets the volume requirement for a large igneous province (LIP). The 3530–3300 Ma stratigraphic successions of the Pilbara and Kaapvaal Cratons are remarkably similar, even including a common volcanic hiatus between about 3426 and 3350 Ma. In the Pilbara, two lines of evidence indicate a magmatic event commencing abruptly at 3530 Ma: firstly, a major peak in the frequency of zircon aged between 3530 and 3490 Ma, preceded by an almost total lack of zircons dated between 3550 and 3530 Ma; and secondly, Lu–Hf isotope evidence for a surge of mantle-derived juvenile magmas between 3530 and 3490 Ma. This sudden magmatic activity is interpreted to coincide with the arrival of the first of a series of mantle plumes that had major impacts on the Paleoarchean crustal evolution of the craton.
Finding the beginning of Earth's fossil record is a long-standing palaeontological challenge arising from the quest to understand the origin of life. Research in recent years has necessarily focused on determining the existence (or otherwise) of fossils in the Early Archaean rock record. Nonetheless, despite numerous reports of microfossils(?) and stromatolites, consensus on the existence of life in the Early Archaean has been elusive (e.g. Moorbath, 2005). However, new techniques and approaches are allowing more confident interpretation of the Archaean fossil record, and the nature of the earliest biosignatures can be used to inform our understanding of emergent ecosystems on Earth and perhaps on other terrestrial planets.
Evidence is mounting that microbial ecosystems may have had a firm foothold as early as ~3.5 Ga (Tice and Lowe, 2004; Schopf, 2006; Hofmann et al., 1999; Allwood et al., 2006, 2007b; Westall et al., 2006; Westall and Southam, 2006). Significantly, there is now also evidence that the Early Archaean record may not be as meager and cryptic as previously thought. For example, the 3.43 Ga Strelley Pool Chert of the Pilbara Craton of Western Australia contains kilometer-scale tracts of a fossilized stromatolite (microbial?) reef (Allwood et al., 2006, 2007b) and provides a large suite of evidence that is consistent with life's existence. Moreover, the rapidity with which the Strelley Pool reef established itself on a newly-submerged landmass suggests that life was well established by that time, waiting in the wings in planktonic form until conditions favored sessile biofilm formation. The rich vault of information in such rocks as the Strelley Pool Chert may shed light not only upon life's antiquity, but also on the nature of early organisms and ecosystems, the environments that nurtured them, the processes that aided preservation of biosignatures and the palaeontological approaches needed to interpret them. This in turn will be a valuable guide in the search for—and interpretation of—ancient microbial biosignatures in the geologic record of other planets or moons.
Carbon isotope fractionation during autotrophic growth of different bacteria which possess different autotrophic CO2 fixation pathways has been studied. l3C/l2C-Ratios in the cell carbon of the following bacteria were determined (CO2 fixation pathway suggested or proven in paren-theses): Alkaligenes eutrophus (reductive pentose phosphate cycle), Desulfobacterium autotrophicum and Acetobacterium woodii (reductive acetyl-CoA pathway). Desulfobacter hydrogenophilus and Thennoproteus neutrophilus (reductive citric acid cycle). The Aδ13C values, which indicate the per mille deviation of the l3C content of cell carbon from that of the CO2 used as the sole carbon source, range from — 10% (reductive citric acid cycle) over —26% (reductive pentose phosphate cycle) to —36%c (reductive acetyl-CoA pathway). Acetate formed via the acetyl-CoA pathway by the acetogenic Acetobacterium woodii showed a Δδ13C = —40%. These data are discussed in view of the different CO2 fixation reactions used by the bacteria and especially with regard to the isotopic composition of sedimentary carbon through time.
The origin of life was an event probably unique in the Earth's history, and reconstructing this event is like assembling a puzzle made up of many pieces. These pieces are composed of information acquired from many different disciplines. The aim of this 1999 book is to integrate discoveries in astronomy, planetology, palaeontology, biology and chemistry, and use this knowledge to present plausible scenarios that give us a better understanding of the likely origin of life on Earth. Twenty-three top experts contribute chapters that discuss everything from the environment and atmosphere of the early Earth, through the appearance of organic molecules in the prebiotic environment, to primitive chiral chemical systems capable of self-replication and evolution by mutation. The book also discusses various clues to the origin of life that can be obtained by a study of the past and present microbial world, as well as from Saturn's moon Titan and the planet Mars. Chemists, biologists, earth scientists, and astronomers will find this book a thought-provoking summary of our knowledge of this extraordinary event.
First published in 1992, The Proterozoic Biosphere was the first major study of the paleobiology of the Proterozoic Earth. It is a multidisciplinary work dealing with the evolution of the Earth, the environment and life during the forty percent of Earth's history that extends from the middle of the Precambrian eon (2500 Ma) to the beginning of the Paleozoic era (550 Ma). The book includes a vast amount of data on Proterozoic organisms and their analogs. Prepared by the Precambrian Paleobiology Research Group, a multidisciplinary consortium of forty-one scientists from eight countries, this monograph was a benchmark in the development of the science of the biochemistry and the organic chemistry of Proterozoic sediments. The study aimed to generate data and analyses based on the re-examination of previous studies and on newer investigations and to build towards the future by placing special emphasis on neglected aspects of paleobiologic study and unsolved problems in the field.
