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  • 1
    Electronic Resource
    Electronic Resource
    Anaerobic methane oxidation associated with marine gas hydrates: superlight C-isotopes from saturated and unsaturated C20 and C25 irregular isoprenoids (1999)
    Springer
    Naturwissenschaften 86 (1999), S. 295-300 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001140050619
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The Cold Carbonate Connection Between Mono Lake, Californiaand the Bransfield Strait, Antarctica (1998)
    Springer
    Aquatic geochemistry 4 (1998), S. 429-454 
    Details
    ISSN: 1573-1421
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Ikaite is a rare form of carbonate – calciumcarbonate hexahydrate (CaCO3·6H2O) and isthe precursor to thinolites. Metastable 'ikaite'crystals, discovered in unconsolidated marinesediments in the King George Basin in the BransfieldStrait, Antarctica, are related to diageneticremineralization reactions of organic matter. StableC, O, and H-isotopes track the response of ikaitecrystals, during growth, to changing interstitialfluid conditions as a result of bacterial sulphatereduction and methanogenesis. Ikaites form inpreference over calcite or aragonite at the prevailingsurface sediment conditions of -1.6 °C and 200bar in the King George Basin. The calcareous tufa towers of the terrestrial,hypersaline Mono Lake of northern California areCaCO3-precipitates formed by the influx ofsubmerged springs of calcium-rich freshwaters enteringthe alkaline lake (ΣCO2 = 0.5 m, pH =9.8). Under current climatic conditions the mineralcalcite precipitates, but during the colder Tiogaglacial period of Late Wisconsian age (12,000 to 9,000years BP), and possibly present day during the winterseason, the monoclinic calcium carbonate hexahydrate(ikaite) was the dominant phase formed. Thesepaleo-ikaites have since recrystallized to form thecalcitic pseudomorph 'thinolites'. They are foundelsewhere in recent and ancient sediments of polarregions, e.g., as 'glendonites'. The environmentaloccurrence of ikaites and their pseudomorphs deem themas potential paleoclimatic indicators of coldenvironments. The larger crystals are typicallyrestricted to colder, deeper organic-rich sediments orin moderately evaporitic basins. In these cases, theikaite formation and decomposition may be influencedby additives such as phosphate or amino acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009696617671
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The Multiple Sources and Patterns of Methane inNorth Sea Waters (1998)
    Springer
    Aquatic geochemistry 4 (1998), S. 403-427 
    Details
    ISSN: 1573-1421
    Keywords: methane ; trace gases ; North Sea ; air-sea exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The methane concentration in the atmosphere andsurface water was surveyed along 58° N acrossthe North Sea. In addition, the vertical methanedistribution in the water column was determined at sixstations along the transect. The methane contents ofthe surface water as well as in the water column wereextremely inhomogeneous. Input by freshwater fromriver discharge and injection of methane from thesediment were both observed. The survey continued fromthe western side of the North Sea to the Elbe Riverestuary. The Elbe River appears to have low methaneconcentrations compared to other European rivers, itsaverage input into the North Sea is estimated to be70 nmol s-1 of methane. Near 58° N,1°40' E, an abandoned drill site releases about 25 % ofthe North Sea's emission of methane to the atmosphere.The advective methane transport induced by watercirculation was assessed for May 16, 1994, using a 3-DNorth Sea circulation model. For the period of thissurvey, the North Sea's source strength foratmospheric methane is estimated using in situwind velocities. In comparison to the advectivetransport by the water circulation, the gas flux tothe atmosphere appears to be the dominant sink ofNorth Sea methane. This flux is estimated to bebetween 1500 · 106 mol a-1 and 3100 ·106mol a-1, depending on the relationbetween wind speed and gas transfer velocity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009644600833
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    Paper (German National Licenses)
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  • 4
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    Introduction to the special issue on SFB 574 “Volatiles and fluids in subduction zones: climate feedback and trigger mechanisms for natural disasters” (2014)
    Springer
    In:  International Journal of Earth Sciences, 103 (7). pp. 1729-1731.
    Details
    Publication Date: 2020-06-26
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00531-014-1059-9
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Past methane release events and environmental conditions at the upper continental slope of the South China Sea: constraints by seep carbonates (2014)
    Springer
    In:  International Journal of Earth Sciences, 103 (7). pp. 1873-1887.
    Details
    Publication Date: 2019-09-23
    Description: Authigenic carbonates and seep biota are archives of seepage history and record paleo-environmental conditions at seep sites. We obtained the timing of past methane release events at the northeastern slope of the South China Sea based on U/Th dating of seep carbonates and seep bivalve fragments from three sites located at 22°02′–22°09′N, 118°43′–118°52′E (water depths from 473 to 785 m). Also, we were able to reconstruct the paleo-bottom water temperatures by calculating the equilibrium temperature using the ages, the corresponding past δ18O of seawater (δ18Osw) and the δ18O of the selected samples formed in contact with bottom seawater with negligible deep fluid influence. A criterion consists of mineralogy, redox-sensitive trace elements and U/Th-isotope systematics is proposed to identify whether the samples were formed from pore water or have been influenced by deep fluid. Our results show that all methane release events occurred between 11.5 ± 0.2 and 144.5 ± 12.7 ka, when sea level was about 62–104 m lower than today. Enhanced methane release during low sea-level stands seems to be modulated by reduced hydrostatic pressure, increased incision of canyons and increased sediment loads. The calculated past bottom water temperature at one site (Site 3; water depth: 767–771 m) during low sea-level stands 11.5 and 65 ka ago ranges from 3.3 to 4.0 °C, i.e., 1.3 to 2.2 °C colder than at present. The reliability of δ18O of seep carbonates and bivalve shells as a proxy for bottom water temperatures is critically assessed in light of 18O-enriched fluids that might be emitted from gas hydrate and/or clay dehydration. Our approach provides for the first time an independent estimate of past bottom water temperatures of the upper continental slope of the South China Sea.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00531-014-1018-5
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Marine cold seeps and their manifestations: geological control, biogeochemical criteria and environmental conditions (2014)
    Springer
    In:  International Journal of Earth Sciences, 103 (7). pp. 1889-1916.
    Details
    Publication Date: 2019-09-23
    Description: Characteristics of cold seeps at different geologic settings are the subject of this review primarily based on results of the Research Consortium SFB 574. Criteria are drawn from examples on the erosive convergent margin off Costa Rica, the accretionary margin off Chile supplemented by examples from the transform margin of the Golf of Cadiz and the convergent Hikurangi margin off New Zealand. Others are from well-studied passive margins of the Black Sea, the Golf of Mexico, the eastern Mediterranean Sea and the South China Sea. Seeps at all settings transport water and dissolved compounds to the ocean through the seafloor by different forcing mechanism and from different depths of the submerged geosphere (10s of meters to 10s of km). The compounds sustain oasis-type ecosystems by providing bioactive reductants sulfide, methane and hydrogen. Hereby, the interaction between fluid composition, flux rates and biota results in a diagnostic hydrocarbon–metazoan–microbe–carbonate association; currently, well over 100 active sites are known. The single most important reaction is microbially mediated anaerobic oxidation of methane with secondary reactions involving S-biogeochemistry and carbonate mineral precipitation. Seep fluids and their seafloor manifestations provide clues as to source depth, fluid–sediment/rock interaction during ascent, lifetime and cyclicity of seepage events but less so on the magnitude of return flow. At erosive margins, Cl-depleted and B-enriched fluids from clay dehydration provide criteria for source depth and temperature. The upward material flow generates mud volcanoes at the seafloor above the projected location of dehydration at depth. At accretionary margins, fluids are derived from more shallow depths by compaction of sediments as they ride on the incoming oceanic plate; they are emitted through thrust faults. At highly sedimented margins, organic-rich and evaporite-containing strata (when present) determine the final fluid composition, by emitting characteristically gas hydrate-derived methane, brine-associated non-methane hydrocarbons or leached elements and their isotopes (Li, δ7Li, B, Ba) from host sediments. Smectite–illite transformation and associated Cl-depletion from release of interlayer water is a pervasive process at these margins. Rare earth element pattern in conjunction with redox-sensitive metals retained in seep carbonates indicate whether or not they precipitated in contact with oxic bottom water or suboxic fluids; clear environmental characterization, though, currently remains inconclusive. More deeply sourced fluids as in transform margins may be characterized by their 87Sr/86Sr ratios from interaction with oceanic crustal rocks below. Quantification of flow and reliable estimates of total volatile output from fore-arcs remain a challenge to seep research, as does understanding the role of geologically derived methane in the global methane cycle.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00531-014-1010-0
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    The alkali reserve of interstitial water at the sites of methane emission in the Sea of Okhotsk (2001)
    Springer
    In:  Geochemistry International, 39 (6). pp. 597-603.
    Details
    Publication Date: 2018-01-19
    Description: The chemical composition (alkalinity, pH, NH4+, PO43-, Si, H2S, Cl-, Ca2+,and SO42-) of interstitial water was studied in the sediments of the Sea of Okhotsk at sites of methane emission. Variations in alkalinity were observed in the sediments from a typical seawater value (2.3 mM/kg) to 63 mM/kg. It is demonstrated that they are caused by the processes of sulfate reduction and methane generation. Based on the balance relationships, an equationwas constructed connecting changes in alkalinity with variations of Ca2+, SO42- and NH4+ in interstitial solutions.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    Styles and productivity of mud diapirism along the Middle American Margin, Part I: Margin evolution, segmentation, dewatering and mud diapirism (2005)
    Springer
    In:  In: Mud volcanoes, geodynamics and seismicity. , ed. by Martinelli, G. and Panahi, B. NATO science series : Series 4, Earth and environmental sciences, 51 . Springer, Dordrecht, pp. 35-48. ISBN 1-402-03203-X
    Details
    Publication Date: 2019-09-23
    Type: Book chapter , PeerReviewed
    DOI: 10.1007/1-4020-3204-8_4
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    OceanRep: Book chapter
  • 9
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    Anaerobic methane oxidation associated with marine gas hydrates: Superlight C-isotopes from saturated and unsaturated C20 and C25 irregular isoprenoids (1999)
    Springer
    In:  Naturwissenschaften, 86 (6). pp. 295-300.
    Details
    Publication Date: 2019-09-23
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s001140050619
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
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    Relations between methane venting, geological structure and seismo-tectonics in the Okhotsk Sea (2004)
    Springer
    In:  Geo-Marine Letters, 24 (3). pp. 135-139.
    Details
    Publication Date: 2019-09-23
    Description: Methane investigations carried out in the Okhotsk Sea show that the methane flux from the earth’s interior into the water column increased during periods of seismo-tectonic activity between 1988 and 2002. In this case, methane gas hydrates found on the northeast Sakhalin slope may have decomposed due to a reactivation of fault zones. Methane emissions in the Okhotsk Sea generally can be divided into two forms. Firstly, methane vents from decomposing gas hydrates and/or free gas exist below gas hydrate saturated sediments via fault zones, venting into the water column with high bubble concentrations that were recorded by echosounding. These hydro-acoustic anomalies were named “flares”. Methane concentration inside these flares reached 10,000–20,000 nl/l (background methane concentrations in the Okhotsk Sea are less than 90–100 nl/l). Secondly, methane migrates as seepage into the water column from oil- and gas-bearing sedimentary source rocks on the eastern Sakhalin shelf, without showing acoustic anomalies in the water column, probably by filtration and diffusion processes. In these areas methane concentration reached 500–3,000 nl/l. In seismo-tectonically active regions, like the northwestern part of the Okhotsk Sea, many new flares were observed. Their distribution and orientation are usually controlled by fault zones (East Sakhalin Shear Zone in the Okhotsk Sea).
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00367-004-0175-0
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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