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Moore KR, Daye M, Gong J, Williford K, Konhauser K, Bosak T. A review of microbial-environmental interactions recorded in Proterozoic carbonate-hosted chert. GEOBIOLOGY 2023; 21:3-27. [PMID: 36268586 PMCID: PMC10092529 DOI: 10.1111/gbi.12527] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 09/14/2022] [Accepted: 09/19/2022] [Indexed: 06/16/2023]
Abstract
The record of life during the Proterozoic is preserved by several different lithologies, but two in particular are linked both spatially and temporally: chert and carbonate. These lithologies capture a snapshot of dominantly peritidal environments during the Proterozoic. Early diagenetic chert preserves some of the most exceptional Proterozoic biosignatures in the form of microbial body fossils and mat textures. This fossiliferous and kerogenous chert formed in shallow marine environments, where chert nodules, layers, and lenses are often surrounded by and encased within carbonate deposits that themselves often contain kerogen and evidence of former microbial mats. Here, we review the record of biosignatures preserved in peritidal Proterozoic chert and chert-hosting carbonate and discuss this record in the context of experimental and environmental studies that have begun to shed light on the roles that microbes and organic compounds may have played in the formation of these deposits. Insights gained from these studies suggest temporal trends in microbial-environmental interactions and place new constraints on past environmental conditions, such as the concentration of silica in Proterozoic seawater, interactions among organic compounds and cations in seawater, and the influence of microbial physiology and biochemistry on selective preservation by silicification.
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Affiliation(s)
- Kelsey R. Moore
- Division of Geological and Planetary SciencesCalifornia Institute of TechnologyPasadenaCaliforniaUSA
| | - Mirna Daye
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
| | - Jian Gong
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
| | | | - Kurt Konhauser
- Department of Earth and Atmospheric SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Tanja Bosak
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
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Wyness AJ, Roush D, McQuaid CD. Global distribution and diversity of marine euendolithic cyanobacteria. JOURNAL OF PHYCOLOGY 2022; 58:746-759. [PMID: 36199189 PMCID: PMC10092097 DOI: 10.1111/jpy.13288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 08/23/2022] [Indexed: 06/16/2023]
Abstract
Euendolithic, or true-boring, cyanobacteria actively erode carbonate-containing substrata in a wide range of environments and pose significant risks to calcareous marine fauna. Their boring activities cause structural damage and increase susceptibility to disease and are projected to only intensify with global climate change. Most research has, however, focused on tropical coral systems, and limited information exists on the global distribution, diversity, and substratum specificity of euendoliths. This metastudy aimed to collate existing 16S rRNA gene surveys along with novel data from the south coast of South Africa to investigate the global distribution and genetic diversity of endoliths to identify a "core endolithic cyanobacterial microbiome" and assess global diversification of euendolithic cyanobacteria. The cyanobacterial families Phormidesmiaceae, Nodosilineaceae, Nostocaceae, and Xenococcaceae were the most prevalent, found in >92% of categories surveyed. All four known euendolith clusters were detected in both intertidal and subtidal habitats, in the North Atlantic, Mediterranean, and South Pacific oceans, across temperate latitudes, and within rock, travertine tiles, coral, shell, and coralline algae substrata. Analysis of the genetic variation within clusters revealed many organisms to be unique to substratum type and location, suggesting high diversity and niche specificity. Euendoliths are known to have important effects on their hosts. This is particularly important when hosts are globally significant ecological engineers or habitat-forming species. The findings of this study indicate high ubiquity and diversity of euendolithic cyanobacteria, suggesting high adaptability, which may lead to increased community and ecosystem-level effects with changing climatic conditions favoring the biochemical mechanisms of cyanobacterial bioerosion.
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Affiliation(s)
- Adam J. Wyness
- Coastal Research GroupDepartment of Zoology and EntomologyRhodes UniversityMakhanda (Grahamstown)South Africa6139
- School of Biology and Environmental SciencesUniversity of MpumalangaMbombelaSouth Africa1200
| | - Daniel Roush
- Center for Fundamental and Applied MicrobiomicsBiodesign InstituteArizona State UniversityTempeArizona85287USA
| | - Christopher D. McQuaid
- Coastal Research GroupDepartment of Zoology and EntomologyRhodes UniversityMakhanda (Grahamstown)South Africa6139
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Roush D, Couradeau E, Guida B, Neuer S, Garcia-Pichel F. A New Niche for Anoxygenic Phototrophs as Endoliths. Appl Environ Microbiol 2018; 84:e02055-17. [PMID: 29222097 PMCID: PMC5795078 DOI: 10.1128/aem.02055-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/29/2017] [Indexed: 02/01/2023] Open
Abstract
Anoxygenic phototrophic bacteria (APBs) occur in a wide range of aquatic habitats, from hot springs to freshwater lakes and intertidal microbial mats. Here, we report the discovery of a novel niche for APBs: endoliths within marine littoral carbonates. In a study of 40 locations around Isla de Mona, Puerto Rico, and Menorca, Spain, 16S rRNA high-throughput sequencing of endolithic community DNA revealed the presence of abundant phylotypes potentially belonging to well-known APB clades. An ad hoc phylogenetic classification of these sequences enabled us to refine the assignments more stringently. Even then, all locations contained such putative APBs, often reaching a significant proportion of all phototrophic sequences. In fact, in some 20% of samples, their contribution exceeded that of oxygenic phototrophs, previously regarded as the major type of endolithic microbe in carbonates. The communities contained representatives of APBs in the Chloroflexales, various proteobacterial groups, and Chlorobi The most abundant phylotypes varied with geography: on Isla de Mona, Roseiflexus and Chlorothrix-related phylotypes dominated, whereas those related to Erythrobacter were the most common in Menorca. The presence of active populations of APBs was corroborated through an analysis of photopigments: bacteriochlorophylls were detected in all samples, bacteriochlorophyll c and a being most abundant. We discuss the potential metabolism and geomicrobial roles of endolithic APBs. Phylogenetic inference suggests that APBs may be playing a role as photoheterotrophs, adding biogeochemical complexity to our understanding of such communities. Given the global extent of coastal carbonate platforms, they likely represent a very large and unexplored habitat for APBs.IMPORTANCE Endolithic microbial communities from carbonates, which have been explored for over 2 centuries in predominantly naturalistic studies, were thought to be primarily composed of eukaryotic algae and cyanobacteria. Our report represents a paradigm shift in this regard, at least for the marine environment, demonstrating the presence of ubiquitous and abundant populations of APBs in this habitat. It raises questions about the role of these organisms in the geological dynamics of coastal carbonates, including coral reefs.
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Affiliation(s)
- Daniel Roush
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Center for Fundamental and Applied Microbiomics, Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Estelle Couradeau
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Laboratoire Biogéosciences, UMR6282, Université de Bourgogne, Dijon, France
| | - Brandon Guida
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Susanne Neuer
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Center for Fundamental and Applied Microbiomics, Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Ferran Garcia-Pichel
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Center for Fundamental and Applied Microbiomics, Biodesign Institute, Arizona State University, Tempe, Arizona, USA
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Abstract
Photoautotrophs assimilate oxidized carbon obtained from one of two sources: dissolved or atmospheric. Despite its size, the pool of lithospheric carbonate is not known to be a direct source for autotrophy. Yet, the mechanism that euendolithic cyanobacteria use to excavate solid carbonates suggests that minerals could directly supply CO2 for autotrophy. Here, we use stable isotopes and NanoSIMS to show that the cyanobacterium Mastigocoleus testarum derives most of its carbon from the mineral it excavates, growing preferentially as an endolith when lacking dissolved CO2. Furthermore, natural endolithic communities from intertidal marine carbonate outcrops present carbon isotopic signatures consistent with mineral-sourced autotrophy. These data demonstrate a direct geomicrobial link between mineral carbonate pools and reduced organic carbon, which, given the geographical extent of carbonate outcrops, is likely of global relevance. The ancient fossil record of euendolithic cyanobacteria suggests that biological fixation of solid carbonate could have been relevant since the mid-Proterozoic.
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Tomescu AMF, Klymiuk AA, Matsunaga KKS, Bippus AC, Shelton GWK. Microbes and the Fossil Record: Selected Topics in Paleomicrobiology. THEIR WORLD: A DIVERSITY OF MICROBIAL ENVIRONMENTS 2016. [DOI: 10.1007/978-3-319-28071-4_3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Bourbin M, Gourier D, Derenne S, Binet L, Le Du Y, Westall F, Kremer B, Gautret P. Dating carbonaceous matter in archean cherts by electron paramagnetic resonance. ASTROBIOLOGY 2013; 13:151-162. [PMID: 23397956 PMCID: PMC3582280 DOI: 10.1089/ast.2012.0855] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 11/07/2012] [Indexed: 06/01/2023]
Abstract
Ancient geological materials are likely to be contaminated through geological times. Thus, establishing the syngeneity of the organic matter embedded in a mineral matrix is a crucial step in the study of very ancient rocks. This is particularly the case for Archean siliceous sedimentary rocks (cherts), which record the earliest traces of life. We used electron paramagnetic resonance (EPR) for assessing the syngeneity of organic matter in cherts that have a metamorphic grade no higher than greenschist. A correlation between the age of Precambrian samples and the shape of their EPR signal was established and statistically tested. As thermal treatments impact organic matter maturity, the effect of temperature on this syngeneity proxy was studied; cyanobacteria were submitted to cumulative short thermal treatment at high temperatures followed by an analysis of their EPR parameters. The resulting carbonaceous matter showed an evolution similar to that of a thermally treated young chert. Furthermore, the possible effect of metamorphism, which is a longer thermal event at lower temperatures, was ruled out for cherts older than 2 Gyr, based on the study of Silurian cherts of the same age and same precursors but various metamorphic grades. We determined that even the most metamorphosed sample did not exhibit the lineshape of an Archean sample. In the hope of detecting organic contamination in Archean cherts, a "contamination-like" mixture was prepared and studied by EPR. It resulted that the lineshape analysis alone does not allow contamination detection and that it must be performed along with cumulative thermal treatments. Such treatments were applied to three Archean chert samples, making dating of their carbonaceous matter possible. We concluded that EPR is a powerful tool to study primitive organic matter and could be used in further exobiology studies on low-metamorphic grade samples (from Mars for example).
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Affiliation(s)
- M. Bourbin
- Biogéochimie et Ecologie des Milieux Continentaux, UMR CNRS 7618, Université Pierre et Marie Curie, Paris, France
| | - D. Gourier
- Laboratoire de Chimie de la Matière Condensée de Paris, Ecole Nationale Supérieure de Chimie de Paris, UMR CNRS 7574, Paris, France
| | - S. Derenne
- Biogéochimie et Ecologie des Milieux Continentaux, UMR CNRS 7618, Université Pierre et Marie Curie, Paris, France
| | - L. Binet
- Laboratoire de Chimie de la Matière Condensée de Paris, Ecole Nationale Supérieure de Chimie de Paris, UMR CNRS 7574, Paris, France
| | - Y. Le Du
- Laboratoire de Chimie de la Matière Condensée de Paris, Ecole Nationale Supérieure de Chimie de Paris, UMR CNRS 7574, Paris, France
| | - F. Westall
- Centre de Biophysique Moléculaire, UPR CNRS 4301, Orléans, France
| | - B. Kremer
- Institute of Paleobiology, Polish Academy of Sciences, Warszawa, Poland
| | - P. Gautret
- CNRS/INSU, ISTO, UMR 7327, Orléans, France
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Ramírez-Reinat EL, Garcia-Pichel F. CHARACTERIZATION OF A MARINE CYANOBACTERIUM THAT BORES INTO CARBONATES AND THE REDESCRIPTION OF THE GENUS MASTIGOCOLEUS(1). JOURNAL OF PHYCOLOGY 2012; 48:740-749. [PMID: 27011091 DOI: 10.1111/j.1529-8817.2012.01157.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A marine, filamentous, endolithic cyanobacterium, strain BC008, was obtained in pure culture and characterized using a polyphasic approach. BC008 could bore into calcium carbonate minerals (calcite, aragonite) and, weakly, into strontium carbonate (strontianite), but not into other carbonates, phosphates, sulfates, silicates, or oxides, including those of calcium. We describe procedures for its continued cultivation in an actively boring state. BC008 was developmentally complex: it displayed lateral, terminal, and intercalary heterocysts; true branching; trichome tapering; and motile hormogonia. It also displayed considerable morphological plasticity between boring and nonboring modes. Boring brought about a halving of trichome diameter, a marked decrease in the ratio of heterocysts to vegetative cells, and a significant preference for lateral versus terminal heterocyst development. The cytoplasm of vegetative cells was filled with 20 nm thick, nanocompartment-like structures of polyhedral appearance and of unknown function. BC008 was capable of complementary chromatic adaptation but did not produce sheath pigments. When boring, it conformed well morphologically to Lagerheim's (1886) description of Mastigocoleus testarum, one of the most common and pervasive bioerosive agents of marine carbonates. We propose strain BC008 as type strain for the species. Multigene (16S rRNA, nif H, rbcL) phylogenies confirm that Mastigocoleus is a distinct, deeply branching genus of cyanobacteria that shares affinities and critical traits with two major taxonomic groups in the heterocystous clade (Nostocales and Stigonematales). We provide a revision of the genus and species descriptions based on our strain and findings.
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Radtke G, Golubic S. Microbial Euendolithic Assemblages and Microborings in Intertidal and Shallow Marine Habitats: Insight in Cyanobacterial Speciation. ADVANCES IN STROMATOLITE GEOBIOLOGY 2011. [DOI: 10.1007/978-3-642-10415-2_16] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Stivaletta N, Barbieri R. Endoliths in Terrestrial Arid Environments: Implications for Astrobiology. CELLULAR ORIGIN, LIFE IN EXTREME HABITATS AND ASTROBIOLOGY 2008. [DOI: 10.1007/978-1-4020-8837-7_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Why are some microorganisms boring? Trends Microbiol 2008; 16:101-6. [DOI: 10.1016/j.tim.2007.12.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 12/10/2007] [Accepted: 12/10/2007] [Indexed: 11/21/2022]
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12
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Abstract
AbstractAbout 65 ichnogenera and a number of bioerosional trace fossils that are unnamed are catalogued with respect to their stratigraphic ranges. In most cases, corresponding stratigraphic studies of the trace-makers are not possible because (1) the rank of taxonomic ascription is too high to be meaningful and (2) not all members of a high taxon are bioeroders. For example, radulation traces of chitons are known from Jurassic to Recent, whereas chitons have a body fossil record back to the Early Palaeozoic. Similarly, whereas the round drill-holeOichnus paraboloidesis known from Cambrian to Recent, the only identified makers of this trace fossil, naticid gastropods, range from Cretaceous to Recent. The stratigraphic ranges of bioerosion ichnotaxa emphasize the two marine revolutions of the Phanerozoic: there is marked increase in diversification during the Ordovician-Devonian interval and since the Triassic.
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Affiliation(s)
- Richard G. Bromley
- Geological Institute, University of Copenhagen Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
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Abstract
Microbial euendoliths (true borer) cyanobacteria are carbonate-boring microorganisms found in modern and ancient marine environments. Modern euendoliths include a wide range of prokaryotes as well as eukaryotes, which have been reported world-wide. The importance of euendolithic cyanobacteria concerns their role in bio-erosion of calcium carbonate substrates and as ecological indicators of shallow, tropical and subtropical marine environments. Arabian Gulf ooids from four sites along the east coast of Saudi Arabia have been bored and inhabited by several species of euendolithic cyanobacteria. This assemblage of different species exists simultaneously within the same ooid grain. Comparisons of 1989 and 1992 data reveal a drastic reduction in active euendoliths, and the average numbers of colonies in these ooids. This study reveals the harmful effect of the 1991 oil spill on these unique microorganisms residing in these ooids.
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Affiliation(s)
- Assad A Al-Thukair
- King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
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Golubic S, Sergeev VN, Knoll AH. Mesoproterozoic Archaeoellipsoides: akinetes of heterocystous cyanobacteria. LETHAIA 1995; 28:285-298. [PMID: 11539549 DOI: 10.1111/j.1502-3931.1995.tb01817.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The genus Archaeoellipsoides Horodyski & Donaldson comprises large (up to 135 micrometers long) ellipsoidal and rod-shaped microfossils commonly found in silicified peritidal carbonates of Mesoproterozoic age. Based on morphometric and sedimentary comparisons with the akinetes of modern bloom-forming Anabaena species, Archaeoellipsoides is interpreted as the fossilized remains of akinetes produced by planktic heterocystous cyanobacteria. These fossils set a minimum date for the evolution of derived cyanobacteria capable of marked cell differentiation, and they corroborate geochemical evidence indicating that atmospheric oxygen levels were well above 1% of present day levels 1,500 million years ago.
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Affiliation(s)
- S Golubic
- Biological Science Center, Boston University, MA 02215, USA
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Schopf JW. Disparate rates, differing fates: tempo and mode of evolution changed from the Precambrian to the Phanerozoic. Proc Natl Acad Sci U S A 1994; 91:6735-42. [PMID: 8041691 PMCID: PMC44277 DOI: 10.1073/pnas.91.15.6735] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Over the past quarter century, detailed genus- and species-level similarities in cellular morphology between described taxa of Precambrian microfossils and extant cyanobacteria have been noted and regarded as biologically and taxonomically significant by numerous workers world-wide. Such similarities are particularly well documented for members of the Oscillatoriaceae and Chroococcaceae, the two most abundant and widespread Precambrian cyanobacterial families. For species of two additional families, the Entophysalidaceae and Pleurocapsaceae, species-level morphologic similarities are supported by in-depth fossil-modern comparisons of environment, taphonomy, development, and behavior. Morphologically and probably physiologically as well, such cyanobacterial "living fossils" have exhibited an extraordinarily slow (hypobradytelic) rate of evolutionary change, evidently a result of the broad ecologic tolerance characteristic of many members of the group and a striking example of G. G. Simpson's [Simpson, G.G. (1944) Tempo and Mode in Evolution (Columbia Univ. Press, New York)] "rule of the survival of the relatively unspecialized." In both tempo and mode of evolution, much of the Precambrian history of life--that dominated by microscopic cyanobacteria and related prokaryotes--appears to have differed markedly from the more recent Phanerozoic evolution megascopic, horotelic, adaptationally specialized eukaryotes.
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Affiliation(s)
- J W Schopf
- Center for the Study of Evolution, University of California, Los Angeles 90024
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Abstract
Microbial mats have descended from perhaps the oldest and most widespread biological communities known. Mats harbor microbes that are crucial for studies of bacterial phylogeny and physiology. They illustrate how several oxygen-sensitive biochemical processes have adapted to oxygen, and they show how life adapted to dry land long before the rise of plants. The search for the earliest grazing protists and metazoa in stromatolites is aided by observations of mats: in them, organic compounds characteristic of ancient photosynthetic protists can be identified. Recent mat studies suggest that the 13C/12C increase observed over geological time in stromatolitic organic matter was driven at least in part by a long-term decline in atmospheric carbon dioxide levels.
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Swett K, Knoll AH. Marine pisolites from Upper Proterozoic carbonates of East Greenland and Spitsbergen. SEDIMENTOLOGY 1989; 36:75-93. [PMID: 11542187 DOI: 10.1111/j.1365-3091.1989.tb00821.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Upper Proterozoic carbonate successions from central East Greenland (the Limestone-Dolomite 'Series' of the Eleonore Bay Group) and Svalbard (the Backlundtoppen Formation of the Akademikerbreen) Group, Spitsbergen, and the Upper Russo Formation of the Raoldtoppen Group, Nordaustlandet) contain thick sequences dominated by pisolites. These rocks were generated in shallow marine environments, and the pisoids are essentially oversized ooids. A marine environment is supported by the thickness and lateral extent of the carbonates; by a sedimentary association of pisolites with stromatolites, flake-conglomerates, calcarenites, calcilutites, microphytolites, and ooids similar to that found in numerous other Proterozoic carbonate successions; by sedimentary structures, including cross-beds and megaripples that characterize the pisolitic beds; and by microorganisms that inhabit modern marine ooids of the Bahama Banks. Petrographic features and strontium abundances suggest that the pisoids were originally aragonitic, but neomorphism, silicification, calcitization, and dolomitization have extensively modified original mineralogies and fabrics. The East Greenland and Svalbard pisolitic carbonates reflect similar depositional environments and diagenetic histories, reinforcing previous bio-, litho-, and chemostratigraphic interpretations that the two sequences accumulated contiguously in a coastal zone of pisoid genesis which extended for at least 600, and probably 1000 or more, kilometres.
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Affiliation(s)
- K Swett
- Department of Geology, The University of Iowa, Iowa City 52242, USA
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18
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Green JW, Knoll AH, Swett K. Microfossils from oolites and pisolites of the Upper Proterozoic Eleonore Bay Group, Central East Greenland. JOURNAL OF PALEONTOLOGY 1988; 62:835-852. [PMID: 11538471 DOI: 10.1017/s0022336000030109] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Silicified oolites and pisolites from Bed 18 of the Upper Proterozoic (about 700-800 Ma) Limestone-Dolomite "Series" of the Eleonore Bay Group, central East Greenland, contain a diverse suite of organically preserved microfossils that is, for the most part. [Of the] assemblages previously described from Proterozoic cherts and shales. Three principal assemblages occur in these rocks: 1) a class bound assemblage found in detrital carbonate grains (now silicified) that served as nuclei for ooid and pisoid growth, as well as in uncoated mud and mat clasts that were carried into the zone of ooid and pisoid deposition; 2) an epilithic and interstitial assemblage consisting of microorganisms that occurred on top of and between grains; and 3) a euendolithic assemblage composed of microbes that actively bored into coated grains. The Upper Proterozoic euendolithic assemblage closely resembles a community of euendolithic cyanobacteria found today in shallow marine ooid sands of the Bahama Banks. Thirteen species are described, of which eight are new, five representing new genera: Eohyella dichotoma n. sp., Eohyella endoatracta n. sp., Eohyella rectoclada n. sp., Thylacocausticus globorum n. gen. and sp., Cunicularius halleri n. gen. and sp., Graviglomus incrustus n. gen. and sp., Perulagranum obovatum n. gen. and sp., and Parenchymodiscus endolithicus n. gen. and sp.
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Affiliation(s)
- J W Green
- University of South Carolina at Spartanburg 29303, USA
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McKay CP. Exobiology and future Mars missions: the search for Mars' earliest biosphere. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1986; 6:269-285. [PMID: 11537831 DOI: 10.1016/0273-1177(86)90096-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The primordial Mars may have possessed a thick carbon dioxide atmosphere, with liquid water common on the surface, similar in many ways to the primordial Earth. During this epoch, billions of years ago, the surface of Mars could have been conducive to the origin of life. It is possible that life evolved on Mars to be later eliminated as the atmospheric pressure dropped. Analysis of the surface of Mars for the traces of this early martian biota could provide many insights into the phenomenon of life and its coupling to planetary evolution.
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Affiliation(s)
- C P McKay
- Solar System Exploration Branch, NASA/Ames Research Center, Moffett Field, CA 94035, USA
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