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Letteratura scientifica selezionata sul tema "Océan archéen"

Autore: Grafiati

Pubblicato: 16 novembre 2024

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Articoli di riviste sul tema "Océan archéen"

Rüpke, Lars, e Fabrice Gaillard. "The Geological History of Water: From Earth’s Accretion to the Modern Deep Water Cycle". Elements 20, n. 4 (1 agosto 2024): 253–58. http://dx.doi.org/10.2138/gselements.20.4.253.

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The abundance of water on Earth and its distribution between surficial and deep reservoirs are the outcome of 4.6 billion years of geological history involving various mechanisms of water in and outgassing. Here, we use the metaphor of a pipeline connecting Earth’s deep and surface water reservoirs. The net flux through this pipeline has changed over time due to contrasting Hadean, Archean, and modern geodynamic regimes. Most water was dissolved in the primordial magma ocean, entrapped in the solidifying mantle, and massively released by volcanism during the Hadean and Archaean. As Earth cooled, plate tectonics enabled water ingassing into the mantle, which appears to exceed outgassing under the modern tectonic regime, implying that Earth’s surface has been drying out and will continue to do so.

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Bano, Nasreen, Shomari Ruffin, Briana Ransom e James T. Hollibaugh. "Phylogenetic Composition of Arctic Ocean Archaeal Assemblages and Comparison with Antarctic Assemblages". Applied and Environmental Microbiology 70, n. 2 (febbraio 2004): 781–89. http://dx.doi.org/10.1128/aem.70.2.781-789.2004.

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ABSTRACT Archaea assemblages from the Arctic Ocean and Antarctic waters were compared by PCR-denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA genes amplified using the Archaea-specific primers 344f and 517r. Inspection of the DGGE fingerprints of 33 samples from the Arctic Ocean (from SCICEX submarine cruises in 1995, 1996, and 1997) and 7 Antarctic samples from Gerlache Strait and Dallman Bay revealed that the richness of Archaea assemblages was greater in samples from deep water than in those from the upper water column in both polar oceans. DGGE banding patterns suggested that most of the Archaea ribotypes were common to both the Arctic Ocean and the Antarctic Ocean. However, some of the Euryarchaeota ribotypes were unique to each system. Cluster analysis of DGGE fingerprints revealed no seasonal variation but supported depth-related differences in the composition of the Arctic Ocean Archaea assemblage. The phylogenetic composition of the Archaea assemblage was determined by cloning and then sequencing amplicons obtained from the Archaea-specific primers 21f and 958r. Sequences of 198 clones from nine samples covering three seasons and all depths grouped with marine group I Crenarchaeota (111 clones), marine group II Euryarchaeota (86 clones), and group IV Euryarchaeota (1 clone). A sequence obtained only from a DGGE band was similar to those of the marine group III Euryarchaeota.

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Béjà, Oded, Eugene V. Koonin, L. Aravind, Lance T. Taylor, Heidi Seitz, Jefferey L. Stein, Daniel C. Bensen, Robert A. Feldman, Ronald V. Swanson e Edward F. DeLong. "Comparative Genomic Analysis of Archaeal Genotypic Variants in a Single Population and in Two Different Oceanic Provinces". Applied and Environmental Microbiology 68, n. 1 (gennaio 2002): 335–45. http://dx.doi.org/10.1128/aem.68.1.335-345.2002.

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ABSTRACT Planktonic crenarchaeotes are present in high abundance in Antarctic winter surface waters, and they also make up a large proportion of total cell numbers throughout deep ocean waters. To better characterize these uncultivated marine crenarchaeotes, we analyzed large genome fragments from individuals recovered from a single Antarctic picoplankton population and compared them to those from a representative obtained from deeper waters of the temperate North Pacific. Sequencing and analysis of the entire DNA insert from one Antarctic marine archaeon (fosmid 74A4) revealed differences in genome structure and content between Antarctic surface water and temperate deepwater archaea. Analysis of the predicted gene products encoded by the 74A4 sequence and those derived from a temperate, deepwater planktonic crenarchaeote (fosmid 4B7) revealed many typical archaeal proteins but also several proteins that so far have not been detected in archaea. The unique fraction of marine archaeal genes included, among others, those for a predicted RNA-binding protein of the bacterial cold shock family and a eukaryote-type Zn finger protein. Comparison of closely related archaea originating from a single population revealed significant genomic divergence that was not evident from 16S rRNA sequence variation. The data suggest that considerable functional diversity may exist within single populations of coexisting microbial strains, even those with identical 16S rRNA sequences. Our results also demonstrate that genomic approaches can provide high-resolution information relevant to microbial population genetics, ecology, and evolution, even for microbes that have not yet been cultivated.

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Robertson, Charles E., John R. Spear, J. Kirk Harris e Norman R. Pace. "Diversity and Stratification of Archaea in a Hypersaline Microbial Mat". Applied and Environmental Microbiology 75, n. 7 (29 dicembre 2008): 1801–10. http://dx.doi.org/10.1128/aem.01811-08.

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ABSTRACT The Guerrero Negro (GN) hypersaline microbial mats have become one focus for biogeochemical studies of stratified ecosystems. The GN mats are found beneath several of a series of ponds of increasing salinity that make up a solar saltern fed from Pacific Ocean water pumped from the Laguna Ojo de Liebre near GN, Baja California Sur, Mexico. Molecular surveys of the laminated photosynthetic microbial mat below the fourth pond in the series identified an enormous diversity of bacteria in the mat, but archaea have received little attention. To determine the bulk contribution of archaeal phylotypes to the pond 4 study site, we determined the phylogenetic distribution of archaeal rRNA gene sequences in PCR libraries based on nominally universal primers. The ratios of bacterial/archaeal/eukaryotic rRNA genes, 90%/9%/1%, suggest that the archaeal contribution to the metabolic activities of the mat may be significant. To explore the distribution of archaea in the mat, sequences derived using archaeon-specific PCR primers were surveyed in 10 strata of the 6-cm-thick mat. The diversity of archaea overall was substantial albeit less than the diversity observed previously for bacteria. Archaeal diversity, mainly euryarchaeotes, was highest in the uppermost 2 to 3 mm of the mat and decreased rapidly with depth, where crenarchaeotes dominated. Only 3% of the sequences were specifically related to known organisms including methanogens. While some mat archaeal clades corresponded with known chemical gradients, others did not, which is likely explained by heretofore-unrecognized gradients. Some clades did not segregate by depth in the mat, indicating broad metabolic repertoires, undersampling, or both.

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Johnson, Benjamin W., e Boswell A. Wing. "Limited Archaean continental emergence reflected in an early Archaean 18O-enriched ocean". Nature Geoscience 13, n. 3 (marzo 2020): 243–48. http://dx.doi.org/10.1038/s41561-020-0538-9.

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Kendall, Brian, Christopher T. Reinhard, Timothy W. Lyons, Alan J. Kaufman, Simon W. Poulton e Ariel D. Anbar. "Pervasive oxygenation along late Archaean ocean margins". Nature Geoscience 3, n. 9 (22 agosto 2010): 647–52. http://dx.doi.org/10.1038/ngeo942.

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Crowe, S. A., C. Jones, S. Katsev, C. Magen, A. H. O'Neill, A. Sturm, D. E. Canfield et al. "Photoferrotrophs thrive in an Archean Ocean analogue". Proceedings of the National Academy of Sciences 105, n. 41 (6 ottobre 2008): 15938–43. http://dx.doi.org/10.1073/pnas.0805313105.

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Busigny, Vincent, Noah J. Planavsky, Didier Jézéquel, Sean Crowe, Pascale Louvat, Julien Moureau, Eric Viollier e Timothy W. Lyons. "Iron isotopes in an Archean ocean analogue". Geochimica et Cosmochimica Acta 133 (maggio 2014): 443–62. http://dx.doi.org/10.1016/j.gca.2014.03.004.

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Corrigan, David, Natasha Wodicka, Christopher McFarlane, Isabelle Lafrance, Deanne Van Rooyen, Daniel Bandyayera e Carl Bilodeau. "Lithotectonic Framework of the Core Zone, Southeastern Churchill Province, Canada". Geoscience Canada 45, n. 1 (20 aprile 2018): 1–24. http://dx.doi.org/10.12789/geocanj.2018.45.128.

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The Core Zone, a broad region located between the Superior and North Atlantic cratons and predominantly underlain by Archean gneiss and granitoid rocks, remained until recently one of the less well known parts of the Canadian Shield. Previously thought to form part of the Archean Rae Craton, and later referred to as the Southeastern Churchill Province, it has been regarded as an ancient continental block trapped between the Paleoproterozoic Torngat and New Quebec orogens, with its relationships to the adjacent Superior and North Atlantic cratons remaining unresolved. The geochronological data presented herein suggest that the Archean evolution of the Core Zone was distinct from that in both the Superior and North Atlantic (Nain) cratons. Moreover, the Core Zone itself consists of at least three distinct lithotectonic entities with different evolutions, referred to herein as the George River, Mistinibi-Raude and Falcoz River blocks, that are separated by steeply-dipping, crustal-scale shear zones interpreted as paleosutures. Specifically, the George River Block consists of ca. 2.70 Ga supracrustal rocks and associated ca. 2.70–2.57 Ga intrusions. The Mistinibi-Raude Block consists of remnants of a ca. 2.37 Ga volcanic arc intruded by a ca. 2.32 Ga arc plutonic suite (Pallatin) and penecontemporaneous alkali plutons (Pelland and Nekuashu suites). It also hosts a coarse clastic cover sequence (the Hutte Sauvage Group) which contains detrital zircons provided from locally-derived, ca. 2.57–2.50 Ga, 2.37–2.32 Ga, and 2.10–2.08 Ga sources, with the youngest concordant grain dated at 1987 ± 7 Ma. The Falcoz River Block consists of ca. 2.89–2.80 Ga orthogneiss intruded by ca. 2.74–2.70 granite, tonalite, and granodiorite. At the western margin of the Core Zone, the George River Block and Kuujjuaq Domain may have been proximal by ca. 1.84 Ga as both appear to have been sutured by the 1.84–1.82 Ga De Pas Batholith, whereas at its eastern margin, the determination of metamorphic ages of ca. 1.85 to 1.80 Ga in the Falcoz River Block suggests protracted interaction with the adjacent Lac Lomier Complex during their amalgamation and suturing, but with a younger, ‘New Quebec’ overprint as well. The three crustal blocks forming the Core Zone add to a growing list of ‘exotic’ Archean to earliest Paleoproterozoic microcontinents and crustal slices that extend around the Superior Craton from the Grenville Front through Hudson Strait, across Hudson Bay and into Manitoba and Saskatchewan, in what was the Manikewan Ocean realm, which closed between ca. 1.83–1.80 Ga during the formation of supercontinent Nuna.RÉSUMÉLa Zone noyau, une vaste région située entre les cratons du Supérieur et de l’Atlantique Nord et reposant principalement sur des gneiss archéens et des roches granitiques, est demeurée jusqu’à récemment l’une des parties les moins bien connues du Bouclier canadien. Considérée auparavant comme faisant partie du craton archéen de Rae, puis comme la portion sud-est de la Province de Churchill, on l’a perçue comme un ancien bloc continental piégé entre les orogènes paléoprotérozoïques des Torngat et du Nouveau-Québec, ses relations avec les cratons supérieurs adjacents et de l’Atlantique Nord demeurant nébuleuses. Les données géochronologiques présentées ici permettent de penser que l’évolution archéenne de la Zone noyau a été différente de celle des cratons du Supérieur et de l’Atlantique Nord (Nain). De plus, la Zone noyau elle-même se compose d’au moins trois entités lithotectoniques distinctes avec des évolutions différentes, appelées ici les blocs de la rivière George, de Mistinibi-Raude et de la rivière Falcoz, lesquels sont séparées par des zones de cisaillement crustales à forte inclinaison, conçues comme des paléosutures. Plus précisément, le bloc de la rivière George est constitué de roches supracrustales d'env. 2,70 Ga, et d’intrusions connexes d'env. 2,70–2,57 Ga. Le bloc Mistinibi-Raude est constitué de vestiges d’un arc volcanique d'env. 2,37 Ga, recoupé par une suite plutonique d’arc d'env. 2,32 Ga (Pallatin) et de plutons alcalins péné-contemporains (suites Pelland et Nekuashu). Il contient également une séquence de couverture clastique grossière (le groupe Hutte Sauvage) renfermant des zircons détritiques de sources locales, âgés d'env. 2,57–2,50 Ga, 2,37–2,32 Ga et 2,10–2,08 Ga, le grain concordant le plus jeune étant âgé de 1987 ± 7 Ma. Le bloc de la rivière Falcoz est formé d’un orthogneiss âgé d'env. 2,89–2,80 Ga, recoupé par des intrusions de granite, tonalite et granodiorite âgées d'env. 2,74–2,70 Ga. À la marge ouest de la Zone noyau, le bloc de la rivière George et du domaine de Kuujjuaq peuvent avoir été proximaux il y a 1,84 Ga env., car les deux semblent avoir été suturés par le batholithe De Pas il y a environ 1,84–1,82 Ga, alors qu’à sa marge est, la détermination des datations métamorphiques de 1,85 à 1,80 Ga dans le bloc de la rivière Falcoz suggère une interaction prolongée avec le complexe adjacent du lac Lomier durant leur amalgamation et leur suture, mais affecté aussi d’une surimpression « Nouveau Québec » plus jeune. Les trois blocs crustaux formant la Zone noyau s’ajoutent à une liste croissante de micro-continents et d’écailles crustales « exotiques » archéennes à paléoprotérozoïques très précoces qui s’étalent autour du craton Supérieur depuis le front de Grenville jusqu’au Manitoba, à travers le détroit d’Hudson, la baie d’Hudson jusque dans le Manitoba et la Saskatchewan, là où s’étendait l’océan Manikewan, lequel s’est refermé il y a environ 1,83–1,80 Ga, pendant la formation du supercontinent Nuna.

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Ouverney, Cleber C., e Jed A. Fuhrman. "Marine Planktonic Archaea Take Up Amino Acids". Applied and Environmental Microbiology 66, n. 11 (1 novembre 2000): 4829–33. http://dx.doi.org/10.1128/aem.66.11.4829-4833.2000.

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ABSTRACT Archaea are traditionally thought of as “extremophiles,” but recent studies have shown that marine planktonic Archaea make up a surprisingly large percentage of ocean midwater microbial communities, up to 60% of the total prokaryotes. However, the basic physiology and contribution of Archaea to community microbial activity remain unknown. We have studied Archaea from 200-m depths of the northwest Mediterranean Sea and the Pacific Ocean near California, measuring the archaeal activity under simulated natural conditions (8 to 17°C, dark and anaerobic) by means of a method called substrate tracking autoradiography fluorescence in situ hybridization (STARFISH) that simultaneously detects specific cell types by 16S rRNA probe binding and activity by microautoradiography. In the 200-m-deep Mediterranean and Pacific samples, cells binding the archaeal probes made up about 43 and 14% of the total countable cells, respectively. Our results showed that the Archaea are active in the uptake of dissolved amino acids from natural concentrations (nanomolar) with about 60% of the individuals in the archaeal communities showing measurable uptake. Bacteria showed a similar proportion of active cells. We concluded that a portion of these Archaea is heterotrophic and also appears to coexist successfully with Bacteria in the same water.

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Più fonti

Tesi sul tema "Océan archéen"

Aquila, Quentin. "Explorer la géochimie des océans archéens avec les Formations de fer rubanées (BIF) : apport des compositions isotopiques Hf-Nd-Pb". Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2024. http://www.theses.fr/2024UCFA0054.

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Les Formations de fer Rubanées (BIF) sont des archives sédimentaires uniques pour étudier les océans primitifs de l'Archéen. Cependant, l'environnement de formation et les mécanismes en jeu dans la formation de ces sédiments chimiques riches en fer et en silicium sont peu contraints. Les BIF ont été très peu étudiés pour leurs compositions isotopiques en Nd-Hf alors qu'elles pourraient permettre d'apporter de nouvelles contraintes sur les sources hydrothermales et continentales alimentant les anciens océans. Pour mieux contraindre l'environnement de formation des BIF, j'ai combiné des aspects de terrains et une étude pétro-géochimique sur une succession sédimentaire de la ceinture de Barberton (3,25 Ga, Afrique du Sud). Le modèle de dépôt des BIF de Barberton implique un milieu de dépôt profond, au bas d'une pente et distal du continent. Cet environnement est perturbé ponctuellement par des dépôts gravitaires terrigènes (mafiques) caractéristiques d'un système sédimentaire d'éventail sous-marin profond. J'ai évalué si la signature géochimique de l'eau de mer (REE+Y, faibles HFSE) permettait d'indiquer la préservation des compositions isotopiques Hf-Nd-Pb primaires sur un BIF de la ceinture de Isua (3,7 Ga, Groenland). Le BIF de Isua montre des perturbations post-dépôts des compositions isotopiques Hf-Nd attribués à la présence d'apatites secondaires. Il a cependant préservé un âge 207Pb-206Pb de 3810 ± 7 Ma hérité de zircons détritiques. Le spectre REE+Y typique de l'eau de mer ne garantit donc ni la préservation des compositions isotopiques Hf-Nd primaires de l'eau de mer, ni de l'absence de toute contamination terrigène. Enfin, j'ai exploré l'origine et la source du Nd et de l'Hf dans les BIF à l'échelle des bandes sur des échantillons provenant de la ceinture de Témagami (2,7 Ga, Canada). Les compositions isotopiques initiales en Nd-Hf des bandes de BIF de Témagami riches en Si montrent un découplage des deux systèmes isotopiques. A l'inverse, celles des bandes riches en Fe demeurent couplées en Nd-Hf. Les bandes riches en Si enregistrent une composition isotopique en Hf radiogénique provenant des eaux d'altérations des continents felsiques. A l'inverse, l'Hf et le Nd des bandes riches en Fe pourrait provenir principalement de l'hydrothermalisme sous-marin
The Banded Iron Formations (BIF) are unique sedimentary archives for studying the primitive oceans of the Archean. However, the environment of formation and the mechanisms involved in the formation of these iron- and silicon-rich chemical sediments are poorly constrained. The BIFs have been little studied for their Nd-Hf isotopic compositions, although they could provide new constraints on the hydrothermal and continental sources feeding the ancient oceans. To better constrain the BIFs environment of formation, I combined field observations with a petro-geochemical study on a sedimentary succession from the Barberton belt (3.25 Ga, South Africa). The deposition model of the Barberton BIFs involves a deep depositional environment, at the base of a slope and distal from the continent. This environment is occasionally disturbed by gravity-driven terrigenous deposits (mafic) characteristics of a deep-sea fan system. I evaluated whether the seawater geochemical signature (REE+Y, low HFSE) indicated the preservation of the primary Hf-Nd-Pb isotopic compositions in a BIF from the Isua belt (3.7 Ga, Greenland). The Isua BIF shows post-depositional disturbances in the Hf-Nd isotopic compositions attributed to the presence of secondary apatites. However, it preserved a 207Pb-206Pb age of 3810 ± 7 Ma inherited from detrital zircons. Therefore, the REE+Y spectrum typical of seawater does not guarantee the preservation of the primary Hf-Nd isotopic compositions of seawater, nor the absence of any terrigenous contamination. Finally, I explored the origin and source of Nd and Hf in the BIFs at the scale of the bands on samples from the Témagami belt (2.7 Ga, Canada). The initial Nd-Hf isotopic compositions of the Si-rich bands of the Témagami BIFs show a decoupling of the two isotopic systems. Conversely, those of the Fe-rich bands remain coupled in Nd-Hf. The Si-rich bands record a radiogenic Hf isotopic composition originating from the weathering waters of felsic continents. Conversely, the Hf and Nd in the Fe-rich bands could mainly originate from submarine hydrothermalism

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Mayaga-Mikolo, Francis. "Chronologie des evenements sedimentaires, magmatiques et tectono-metamorphiques du precambrien d'afrique centrale occidentale (gabon) : tectogenese ogooue et heritage archeen". Clermont-Ferrand 2, 1996. http://www.theses.fr/1996CLF21824.

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Le precambrien du gabon est compose de terrains archeens des massifs du nord-gabon et du chaillu, des formations reputees d'age paleoproterozoique de l'ogooue, des sediments paleoproterozoiques du francevillien, des plutons d'age eburneen du mayombe (ou chaine ouest-congolienne). Des datations radiometriques (pb-pb, u-pb, rb-sr et sm-nd, ar-ar) ont ete utilisees afin de contraindre l'age des evenements sedimentaires, magmatiques, tectoniques et metamorphiques qui ont affecte ces differentes entites. L'etude geochronologique montre que l'accretion des terrains paleoproterozoiques se fait autour des noyaux archeens dont les plus vieux temoins, d'age anterieur a 3100 ma, seraient presents dans les monts de cristal au nord-gabon. L'histoire archeenne se deroulerait ensuite de la facon suivante: entre 3100-3000 ma: premier metamorphisme de haut grade ; 3000-2950 ma: mise en place diachrone des greenstone belts. Durant la meme periode et jusqu'a 2850 ma des intrusions granitiques a tonalitiques se mettent en place. Elles provoquent dans l'encaissant, soit des recristallisations dans des conditions granulitiques, soit des retromorphoses. L'evolution archeenne s'acheve entre 2800 et 2500 ma, avec la mise en place des ultrabasiques de kinguele, des leucogranites, des pegmatites, des monzonites et des granites. Ces processus diapiriques fini-archeens de grande ampleur associes a une tectonique verticale vont favoriser l'apparition, a partir de 2500 ma, des premiers bassins sedimentaires tels que l'ogooue. Ce dernier sera ensuite engage dans un orogene paleoproterozoique qui s'accompagne d'une remobilisation de materiel archeen. Les trois phases tectono-metamorphiques d1, d2 et d3 responsables de sa structuration en domaine orogenique collisionnel sont respectivement posterieure a 2440 ma, syn-2120 ma et syn-a post 2040-2000 ma. Parallelement les metabasites de l'ogooue, reputees pre-orogeniques s'avereraient etre d'age archeen. Les contraintes ar-ar sur l'age des mineralisations d'eteke associees a l'evolution tectono-metamorphique du domaine de l'ogooue n'ont revele que des ages de refroidissement autour de 1850-1870 ma. Les sediments fluvio-deltaiques du francevillien moyen a superieur (2050-1780 ma) s'individualisent a la fin de cette evolution tectonique collisionnelle, en position d'avant-pays. Parallelement, les investigations rb-sr dans la faille syn-d3 de l'ikoye-ikobe ont revele un rejeu panafricain de celle-ci vers 530 ma. Enfin, la comparaison de l'histoire geologique de la partie occidentale du craton du congo avec le craton de sao francisco (bresil), montre qu'en ce qui concerne les blocs archeens, les plus vieux temoins de l'histoire archeenne precoce ne sont nettement reconnus qu'au bresil (3200-3400 ma), en revanche au paleoproterozoique, de part et d'autre de l'atlantique, les processus geodynamiques et orogeniques sont similaires

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Koeksoy, Elif [Verfasser], e Andreas [Akademischer Betreuer] Kappler. "Biogeochemical Fe-S-cycling in a late Archean and Proterozoic ocean model habitat - the high alpine Arvadi Spring / Elif Koeksoy ; Betreuer: Andreas Kappler". Tübingen : Universitätsbibliothek Tübingen, 2018. http://d-nb.info/1198973374/34.

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Halter, Ghislaine. "Zonalite des alterations dans l'environnement des gisements d'uranium associes a la discordance du proterozoique moyen (saskatchewan, canada)". Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13078.

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Cette etude porte sur les conditions des gisements d'uranium du saskatchewan de la region de waterbury lake, qui sont associes a la discordance entre le socle archeen/aphebien et la couverture sedimentaire helikienne. Deux episodes tardi-hudsoniens gouvernent la remobilisation in situ de l'uranium: une retromorphose (facies schiste vert) et une alteration hydrothermale affectant les zones tectonisees du socle. Les donnees isotopiques des phyllites revelent que la diagenese des gres est realisee en presence d'une saumure qui est egalement a l'origine du fluide mineralisateur

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Barbeau, David Longfellow Jr. "Application of Growth Strata and Detrital-Zircon Geochronology to Stratigraphic Architecture and Kinematic History". Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/244092.

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Growth strata analysis and detrital-zircon geochronology are useful applications of stratigraphy to tectonic problems. Whereas both tools can contribute to kinematic analyses of supracrustal rock bodies, growth strata are also useful for analyzing the influence of tectonics on stratigraphic architecture. This study reports: 1) a conceptual model for growth strata development; 2) stratigraphic and kinematic analyses of growth strata architectures from growth structures in southeastern Utah, the Gulf of Mexico, and northeastern Spain; and 3) the detrital-zircon geochronology of the Salinian block of central coastal California. Kinematic sequence stratigraphy subdivides growth strata into kinematic sequences that are separated by kinematic sequence boundaries. Kinematic sequences can be further partitioned into kinematic domains based on the termination patterns of strata within a kinematic sequence. Salt- related fluvial growth strata from the Gulf of Mexico and southeastern Utah contain stratigraphic architectures that are unique to different kinematic domains. Offlap kinematic domains contain fluvial strata indicative of high slopes, low accommodation rates, and strong structural influence on paleocurrent direction. Onlap kinematic domains contain fluvial strata indicative of moderate slopes, high accommodation rates, and decreased structural influence on paleocurrent direction. The stratigraphic architecture of alluvial -fan thrust -belt growth strata in northeastern Spain does not display a marked correlation with kinematic domain, and is most easily interpreted using existing models for autocyclic alluvial -fan evolution. Detrital- zircon (U -Pb) geochronologic data from basement and cover rocks of Salinia suggest that Salinia originated along the southwestern margin of North America, likely in the vicinity of the Mojave Desert. The presence of Neoproterozoic and Late Archean detrital zircons in Salinian basement rocks also suggest that Salinian sediments were recycled from miogeoclinal sediments of the western margin of North America.

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Libri sul tema "Océan archéen"

Enright, Joseph F. Shinano!: The sinking of Japan's secret supership. London: Bodley Head, 1987.

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Enright, Joseph F. Shinano!: The sinking of Japan's secret supership. Taiwan: Xing Guang, 1987.

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Robinson, Carol. Phytoplankton Biogeochemical Cycles. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199233267.003.0005.

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This chapter describes how the activity of phytoplankton, bacteria, and Archaea drive the marine biogeochemical cycles of carbon, nitrogen, and phosphorus, and how climate driven changes in plankton abundance and community composition influence these biogeochemical cycles in the North Atlantic Ocean and adjacent seas. Carbon, nitrogen, and phosphorus are essential elements required for all life on Earth. In the marine environment, dissolved inorganic carbon, nitrogen, and phosphorus are utilized during phytoplankton growth to form organic material, which is respired and remineralized back to inorganic forms by the activity of bacteria, Archaea, and zooplankton. The net result of the photosynthesis, calcification, and respiration of marine plankton is the uptake of carbon dioxide from the atmosphere, its sequestration to the deep ocean as organic and inorganic carbon, and its availability to fuel all fish and shellfish production.

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Money, Nicholas P. 6. Microbial ecology and evolution. Oxford University Press, 2014. http://dx.doi.org/10.1093/actrade/9780199681686.003.0006.

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Many ecosystems are wholly microbial and the activities of microorganisms provide the biochemical foundation for plant and animal life. ‘Microbial ecology and evolution’ describes how plants depend upon the complex redox reactions of microbes that fertilize the soil by fixing nitrogen, converting nitrites to nitrates, enhancing the availability of phosphorus and trace elements, and recycling organic matter. Eukaryotic microorganisms are similarly plentiful and essential for the sustenance of plants and animals. Bacteria, archaea, and single-celled eukaryotes are the masters of the marine environment, harnessing the energy that supports complex ecological interactions between aquatic animals. Bacteria and archaea form 90% of the ocean biomass and surface waters are filled with eukaryotic algae.

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Kirchman, David L. Community structure of microbes in natural environments. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789406.003.0004.

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Community structure refers to the taxonomic types of microbes and their relative abundance in an environment. This chapter focuses on bacteria with a few words about fungi; protists and viruses are discussed in Chapters 9 and 10. Traditional methods for identifying microbes rely on biochemical testing of phenotype observable in the laboratory. Even for cultivated microbes and larger organisms, the traditional, phenotype approach has been replaced by comparing sequences of specific genes, those for 16S rRNA (archaea and bacteria) or 18S rRNA (microbial eukaryotes). Cultivation-independent approaches based on 16S rRNA gene sequencing have revealed that natural microbial communities have a few abundant types and many rare ones. These organisms differ substantially from those that can be grown in the laboratory using cultivation-dependent approaches. The abundant types of microbes found in soils, freshwater lakes, and oceans all differ. Once thought to be confined to extreme habitats, Archaea are now known to occur everywhere, but are particularly abundant in the deep ocean, where they make up as much as 50% of the total microbial abundance. Dispersal of bacteria and other small microbes is thought to be easy, leading to the Bass Becking hypothesis that “everything is everywhere, but the environment selects.” Among several factors known to affect community structure, salinity and temperature are very important, as is pH especially in soils. In addition to bottom-up factors, both top-down factors, grazing and viral lysis, also shape community structure. According to the Kill the Winner hypothesis, viruses select for fast-growing types, allowing slower growing defensive specialists to survive. Cultivation-independent approaches indicate that fungi are more diverse than previously appreciated, but they are less diverse than bacteria, especially in aquatic habitats. The community structure of fungi is affected by many of the same factors shaping bacterial community structure, but the dispersal of fungi is more limited than that of bacteria. The chapter ends with a discussion about the relationship between community structure and biogeochemical processes. The value of community structure information varies with the process and the degree of metabolic redundancy among the community members for the process.

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Capitoli di libri sul tema "Océan archéen"

Shen, Yanan, Daniele L. Pinti e Ko Hashizume. "Biogeochemical cycles of sulfur and nitrogen in the Archean ocean and atmosphere". In Archean Geodynamics and Environments, 305–20. Washington, D. C.: American Geophysical Union, 2006. http://dx.doi.org/10.1029/164gm19.

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Takai, Ken, Fumio Inagaki e Koki Horikoshi. "Distribution of unusual archaea in subsurface biosphere". In The Subseafloor Biosphere at Mid-Ocean Ridges, 369–81. Washington, D. C.: American Geophysical Union, 2004. http://dx.doi.org/10.1029/144gm23.

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Volk, Tyler, e Martin I. Hoffert. "Ocean Carbon Pumps: Analysis of Relative Strengths and Efficiencies in Ocean-Driven Atmospheric CO2 Changes". In The Carbon Cycle and Atmospheric CO2 : Natural Variations Archean to Present, 99–110. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm032p0099.

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Hsü, Kenneth J., e Judith A. Mckenzie. "A “Strangelove” Ocean in the Earliest Tertiary". In The Carbon Cycle and Atmospheric CO2 : Natural Variations Archean to Present, 487–92. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm032p0487.

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Wenk, T., e U. Siegenthaler. "The High-Latitude Ocean as a Control of Atmospheric CO2". In The Carbon Cycle and Atmospheric CO2 : Natural Variations Archean to Present, 185–94. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm032p0185.

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Mclean, Dewey M. "Mantle Degassing Induced Dead Ocean in the Cretaceous-Tertiary Transition". In The Carbon Cycle and Atmospheric CO2 : Natural Variations Archean to Present, 493–503. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm032p0493.

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Herring, James R. "Charcoal Fluxes into Sediments of the North Pacific Ocean: The Cenozoic Record of Burning". In The Carbon Cycle and Atmospheric CO2 : Natural Variations Archean to Present, 419–42. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm032p0419.

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Peterson, L. C., e W. L. Prell. "Carbonate Preservation and Rates of Climatic Change: An 800 KYR Record from the Indian Ocean". In The Carbon Cycle and Atmospheric CO2 : Natural Variations Archean to Present, 251–69. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm032p0251.

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Toggweiler, J. R., e J. L. Sarmiento. "Glacial to Interglacial Changes in Atmospheric Carbon Dioxide: The Critical Role of Ocean Surface Water in High Latitudes". In The Carbon Cycle and Atmospheric CO2 : Natural Variations Archean to Present, 163–84. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm032p0163.

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Curry, W. B., e G. P. Lohmann. "Carbon Deposition Rates and Deep Water Residence Time in the Equatorial Atlantic Ocean Throughout the Last 160,000 Years". In The Carbon Cycle and Atmospheric CO2 : Natural Variations Archean to Present, 285–301. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm032p0285.

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Atti di convegni sul tema "Océan archéen"

Lambrecht, Nicholas, Elizabeth Swanner, Chad Wittkop, Cody Sheik e Sergei Katsev. "MICROBIAL COMMUNITIES OF TWO ARCHEAN OCEAN ANALOGS". In 52nd Annual North-Central GSA Section Meeting - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018nc-312978.

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Zheng, Xin-Yuan, Aaron M. Satkoski, Brian L. Beard, Thiruchelvi R. Reddy, Nicolas J. Beukes e Clark M. Johnson. "TRACING OF THE COUPLED SI AND FE CYCLE IN THE ARCHEAN OCEAN". In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-300243.

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Hinz, Isaac L., Christine Nims, Christine Nims, Samantha Theuer, Samantha Theuer, Alexis S. Templeton, Alexis S. Templeton, Jena E. Johnson e Jena E. Johnson. "FERRIC IRON CATALYZES THE FORMATION OF IRON-RICH SILICATES UNDER ARCHEAN OCEAN-LIKE CONDITIONS". In 54th Annual GSA North-Central Section Meeting - 2020. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020nc-347861.

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Ribeiro, Elton J. B., Edson Luiz Labanca, Cesar Bartz e Andre Iwane. "Tubarão Martelo Field Development: Lazy S Riser Configuration Using Mid Water Arch (MWA)". In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41873.

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Mid-Water Arches (MWAs) have been used as alternative to distributed buoyancy systems in flexible riser designs worldwide. Those structures usually involve complex lifting requirements for installation, as the Buoyancy Tank Assemblies (BTAs) are lightweight compared to its volume and footprint area. Handling those odd-sized structures in the deck of a construction vessel and crossing the splash-zone are frequently challenging engineering tasks. This paper will present a case study of MWA installation performed by GE/WSC as part of the OGX Tubarão Martelo field development, offshore Brazil. The location is prone to swell from South Atlantic and hence a flat sea is a rare event, even when no local wind generated are present. This makes any delicate and weather sensitive operation a critical schedule issue. Still, 8 MWA were installed with minor Waiting on Weather thanks to an extensive analysis envelope and to an engineered installation method aiming to minimize the time the operation was limited by weather condition. Also, as the scope involved a large number of MWAs, a “mass production” method was developed for the operations, not only covering the offshore installation but also the mobilization and logistic aspects of handling large and heavy items ashore. To allow road transportation by trucks, the BTAs and Gravity Bases (GBs) were shipped to the mobilization port in sub-components for site integration.

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Murray, John J., Harish Mukundan, Apurva Gupta e Guibog Choi. "Dry Disconnectable Riser System for Low Keel Clearance Floaters". In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79734.

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Fixed structures operating in extreme offshore environments (eg: arctic) have to resist and survive the challenging conditions like large ice forces. On the other hand, the floating systems in such environments benefit from their ability to be evacuated and transported in the event of severe condition. However, such an ice-management scheme requires the moorings and risers to be disconnected in the severe conditions and reconnected during more clement conditions. Among the floater designs typically considered for extreme offshore applications is the Spar. The Spar offers low extreme motion responses than other shallower draft floaters and as a result, low fatigue damage on the risers. However, this design has versions with open centerwells that can contain leaked product and cause a potential hazardous condition. Furthermore, most designs that require the risers to be disconnected below the mean water line (wet-disconnection mechanism) not only carry the risk of leakage but have poor access for visual inspection. One solution is to use a continuous flexible riser without in-line connections or terminations in the flexible riser between the seafloor pipe line end manifolds (PLEM) and the production deck manifolds (dry-disconnection mechanism). The risers disconnect at an elevation above the water line and the termination point is lowered to a disconnect buoy supported at the keel. Subsequently the floater is moved away. The main difficulty is that the lowered flexible riser has to be suspended from the disconnect buoy and at the same time avoid contact with the seafloor. This paper describes and discusses a design of a dry-disconnectable flexible riser system comprised of a buoy supporting arches to control the bending in the risers during operation and disconnect. The system is particularly effective when the clearance between the keel and the seafloor is restricted. The rationale is based on strength, control of the minimum allowable bend radius and interference among the risers.

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Rapporti di organizzazioni sul tema "Océan archéen"

Barbie, Alexander. ARCHES Digital Twin Framework. GEOMAR, dicembre 2022. http://dx.doi.org/10.3289/sw_arches_core_1.0.0.

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In the Helmholtz Future Project ARCHES (Autonomous Robotic Networks to Help Modern Societies) with a consortium of partners from AWI (Alfred- Wegener-Institute Helmholtz Centre for Polar and Marine Research), DLR (German Aerospace Center), KIT (Karlsruhe Institute of Technology), and the GEOMAR (Helmholtz Centre for Ocean Research Kiel), several Digital Twins of ocean observation systems were developed by the GEOMAR and AWI. The ARCHES Digital Twin Framework is one of the results of this project. The software is based on the Robot Operating System (ROS) and is written in Python.

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Mueller, C., S. J. Piercey, M. G. Babechuk e D. Copeland. Stratigraphy and lithogeochemistry of rocks from the Nugget Pond Deposit area, Baie Verte Peninsula, Newfoundland. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328989.

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Stratigraphic and lithogeochemical data were collected from selected drill core from the Nugget Pond gold deposit in the Betts Cove area, Newfoundland. The stratigraphy consists of a lower unit of basaltic rocks that are massive to pillowed (Mount Misery Formation). This is overlain by sedimentary rocks of the Scrape Point Formation that consist of lower unit of turbiditic siltstone and hematitic cherts/iron formations (the Nugget Pond member); the unit locally has a volcaniclastic rich-unit at its base and grades upwards into finer grained volcaniclastic/turbiditic rocks. This is capped by basaltic rocks of the Scrape Point Formation that contain pillowed and massive mafic flows that are distinctively plagioclase porphyritic to glomeroporphyritic. The mafic rocks of the Mount Misery Formation have island arc tholeiitic affinities, whereas Scrape Point Formation mafic rocks have normal mid-ocean ridge (N-MORB) to backarc basin basalt (BABB) affinities. One sample of the latter formation has a calc-alkalic affinity. All of these geochemical features are consistent with results and conclusions from previous workers in the area. Clastic sedimentary rocks and Fe-rich sedimentary rocks of the Scrape Point Formation have features consistent with derivation from local, juvenile sources (i.e., intra-basinal mafic rocks). The Scrape Point Formation sedimentary rocks with the highest Fe/Al ratios, inferred to have greatest amount of hydrothermally derived Fe, have positive Ce anomalies on Post-Archean Australian Shale (PAAS)-normalized trace element plots. These features are consistent with having formed via hydrothermal venting into an anoxic/ sub-oxic water column. Further work is needed to test whether these redox features are a localized feature (i.e., restricted basin) or a widespread feature of the late Cambrian-early Ordovician Iapetus Ocean, as well as to delineate the role that these Fe-rich sedimentary rocks have played in the localization of gold mineralization within the Nugget Pond deposit.

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Thomas, M. D. Magnetic and gravity characteristics of the Thelon and Taltson orogens, northern Canada: tectonic implications. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329250.

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Differences of opinion concerning the relationship between the Thelon tectonic zone and the Taltson magmatic zone, as to whether they are individual tectonic elements or two independent elements, have generated various plate tectonic models explaining their creation. Magnetic and gravity signatures indicate that they are separate entities and that the Thelon tectonic zone and the Great Slave Lake shear zone form a single element. Adopting the single-element concept and available age dates, a temporally evolving plate tectonic model of Slave-Rae interaction is presented. At 2350 Ma, an Archean supercontinent rifted along the eastern and southern margins of the Slave Craton. Subsequent ocean closure, apparently diachronous, began with subduction at 2070 Ma in the northern Thelon tectonic zone, followed by subduction under the Great Slave Lake shear zone at 2051 Ma. Subduction related to closure of an ocean between the Buffalo Head terrane and the Rae Craton initiated under the Taltson magmatic zone at 1986 Ma, at which time subduction continued along the Thelon tectonic zone. At 1970 Ma, collision in the northern Thelon tectonic zone is evidenced in the Kilohigok Basin. From 1957 to 1920 Ma, plutonism was active in the Taltson magmatic zone, Great Slave Lake shear zone, and southern Thelon tectonic zone. The plutonism terminated in the northern Thelon tectonic zone at 1950 Ma, but it resumed at 1910 Ma and continued until 1880 Ma. The East Arm Basin witnessed igneous activity as early as 2046 Ma, though this took place more continuously from 1928 to 1861 Ma; some igneous rocks bear subduction-related trace element signatures. These signatures, and the presence of northwest-verging nappes, may signify collision with the Great Slave Lake shear zone as a result of southeastward subduction, completing closure between the Slave and Rae cratons.

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Sommer, Stefan, Sascha Flögel, Michael Walter e Frank Wenzhöfer. Autonomous Robotic Network to Resolve Coastal Oxygen Dynamics : Cruise No. AL547, 20.10. – 31.10.2020, Kiel – Kiel, ARCODYN. GEOMAR Helmholtz Centre for Ocean Research Kiel, 2022. http://dx.doi.org/10.3289/cr_al547.

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The ALKOR cruise AL547 represents a concluding milestone of the Helmholtz innovation project ARCHES (Autonomous Robotic Networks to Help Modern Societies). The aim was to implement a heterogeneous robotic sensing network to simultaneously monitor changes in the water column and at the seafloor. The network has been developed by a consortium of partners from AWI, DLR, GEOMAR and the University of Kiel. The participating sensing platforms allow for real-time data transfer and the entire network shall be able to autonomously respond to environmental changes in the ocean. The network comprised seven different mobile and stationary platforms. Tests were conducted at the Mittelgrund working area in the entrance of the Eckernförde Bay (western Baltic Sea). During 47 stations the various sensing platforms were deployed and recovered for maintenance. A total of 87853 messages were sent using hydro-acoustics, of which 71734 messages contained O 2 data, 15177 were status messages, 926 messages were commands to trigger a change of the measurement behavior of a platform and 16 messages represented broadcasts about the environmental status. We synoptically recorded short-term O 2 time series on the different platforms, which were placed along a depth gradient in the working area. As the Eckernförde Bay is known for sporadic fish kills by anoxia we hope to contribute to a better understanding of the O 2 dynamics in coastal areas. - (ALKOR-Berichte ; AL547)

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Mueller, C., S. J. Piercey, M. G. Babechuk e D. Copeland. Stratigraphy and lithogeochemistry of the Goldenville horizon and associated rocks, Baie Verte Peninsula, Newfoundland. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328990.

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The Goldenville horizon in the Baie Verte Peninsula is an important stratigraphic horizon that hosts primary (Cambrian to Ordovician) exhalative magnetite and pyrite and was a chemical trap for younger (Silurian to Devonian) orogenic gold mineralization. The horizon is overlain by basaltic flows and volcaniclastic rocks, is intercalated with variably coloured argillites and cherts, and underlain by mafic volcaniclastic rocks; the entire stratigraphy is cut by younger fine-grained mafic dykes and coarser gabbro. Lithogeochemical signatures of the Goldenville horizon allow it to be divided into high-Fe iron formation (HIF; &gt;50% Fe2O3), low-Fe iron formation (LIF; 15-50% Fe2O3), and argillite with iron minerals (AIF; &lt;15% Fe2O3). These variably Fe-rich rocks have Fe-Ti-Mn-Al systematics consistent with element derivation from varying mineral contributions from hydrothermal venting and ambient detrital sedimentation. Post-Archean Australian Shale (PAAS)-normalized rare earth element (REE) signatures for the HIF samples have negative Ce anomalies and patterns similar to modern hydrothermal sediment deposited under oxygenated ocean conditions. The PAAS-normalized REE signatures of LIF samples have positive Ce anomalies, similar to hydrothermal sediment deposited under anoxic to sub-oxic conditions. The paradoxical Ce behaviour is potentially explained by the Mn geochemistry of the LIF samples. The LIF have elevated MnO contents (2.0-7.5 weight %), suggesting that Mn from hydrothermal fluids was oxidized in an oxygenated water column during hydrothermal venting, Mn-oxides then scavenged Ce from seawater, and these Mn-oxides were subsequently deposited in the hydrothermal sediment. The Mn-rich LIF samples with positive Ce anomalies are intercalated with HIF with negative Ce anomalies, both regionally and on a metre scale within drill holes. Thus, the LIF positive Ce anomaly signature may record extended and particle-specific scavenging rather than sub-oxic/redox-stratified marine conditions. Collectively, results suggest that the Cambro-Ordovician Taconic seaway along the Laurentian margin may have been completely or near-completely oxygenated at the time of Goldenville horizon deposition.

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