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  • Elsevier  (12)
  • Inter Research  (3)
  • Ernst & Sohn  (2)
  • ASLO (Association for the Sciences of Limnology and Oceanography)  (1)
  • Bremen : Fachbereich Geowissenschaften, Universität Bremen  (1)
  • 1
    Book
    Book
    Report and preliminary results of R/V Poseidon cruise P317/4 [POS317/4] : Istanbul-Istanbul, 16 October - 4 November 2004 (2004)
    Bremen : Fachbereich Geowissenschaften, Universität Bremen
    Details Availability
    Keywords: Fahrtbericht ; Schwarzes Meer ; Methan ; Gashydrate
    Type of Medium: Book
    Pages: 68 Seiten , Karten, Illustrationen, Diagramme , 30 cm
    Series Statement: Berichte aus dem Fachbereich Geowissenschaften der Universität Bremen No. 235
    Language: English
    Note: Literaturverz. S. 67 - 68
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  • 2
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    Molecular and isotopic partitioning of low-molecular-weight hydrocarbons during migration and gas hydrate precipitation in deposits of a high-flux seepage site (2010)
    Elsevier
    In:  Chemical Geology, 269 (3/4). pp. 350-363.
    Details
    Publication Date: 2019-09-23
    Description: Detailed knowledge of the extent of post-genetic modifications affecting shallow submarine hydrocarbons fueled from the deep subsurface is fundamental for evaluating source and reservoir properties. We investigated gases from a submarine high-flux seepage site in the anoxic Eastern Black Sea in order to elucidate molecular and isotopic alterations of low-molecular-weight hydrocarbons (LMWHC) associated with upward migration through the sediment and precipitation of shallow gas hydrates. For this, near-surface sediment pressure cores and free gas venting from the seafloor were collected using autoclave technology at the Batumi seep area at 845 m water depth within the gas hydrate stability zone. Vent gas, gas from pressure core degassing, and from hydrate dissociation were strongly dominated by methane (〉 99.85 mol.% of ∑[C1–C4, CO2]). Molecular ratios of LMWHC (C1/[C2 + C3] 〉 1000) and stable isotopic compositions of methane (δ13C = − 53.5‰ V-PDB; D/H around − 175‰ SMOW) indicated predominant microbial methane formation. C1/C2+ ratios and stable isotopic compositions of LMWHC distinguished three gas types prevailing in the seepage area. Vent gas discharged into bottom waters was depleted in methane by 〉 0.03 mol.% (∑[C1–C4, CO2]) relative to the other gas types and the virtual lack of 14C–CH4 indicated a negligible input of methane from degradation of fresh organic matter. Of all gas types analyzed, vent gas was least affected by molecular fractionation, thus, its origin from the deep subsurface rather than from decomposing hydrates in near-surface sediments is likely. As a result of the anaerobic oxidation of methane, LMWHC in pressure cores in top sediments included smaller methane fractions [0.03 mol.% ∑(C1–C4, CO2)] than gas released from pressure cores of more deeply buried sediments, where the fraction of methane was maximal due to its preferential incorporation in hydrate lattices. No indications for stable carbon isotopic fractionations of methane during hydrate crystallization from vent gas were found. Enrichments of 14C–CH4 (1.4 pMC) in short cores relative to lower abundances (max. 0.6 pMC) in gas from long cores and gas hydrates substantiates recent methanogenesis utilizing modern organic matter deposited in top sediments of this high-flux hydrocarbon seep area.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.chemgeo.2009.10.009
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Aktive Fluidaustritte im Aleutengraben, Geologie und Biologie der Cold Vents im Golf von Alaska (1997)
    Ernst & Sohn
    In:  Geowissenschaften, 15 (6). pp. 200-204.
    Details
    Publication Date: 2019-09-23
    Description: Active fluid venting was observed for the first time along the Aleutian convergent margin during RV SONNE cruise 97. These subduction-induced cold vents were subsequently investigated in detail during cruise SO 110 in the summer of 1996 using the Canadian remotely operated vehicle, ROPOS. Active sites of dewatering were found at the youngest deformation structure adjacent to the decollement zone. High concentrations of reduced gases in the escaping fluids provide the nutritional and energy basis for the observed chemosynthetic communities in which clams and tubeworms dominate. Further evidence for fluid venting comes from the mineral precipitates of barite and carbonates.
    Type: Article , NonPeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - without review
  • 4
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    Methanhydratfund von FS SONNE vor der Westküste Nordamerikas (1997)
    Ernst & Sohn
    In:  Geowissenschaften, 6 . pp. 194-199.
    Details
    Publication Date: 2018-12-19
    Type: Article , NonPeerReviewed
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    OceanRep: Article in a Scientific Journal - without review
  • 5
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    16S rDNA-based phylogeny of sulfur-oxidizing bacterial endosymbionts in marine bivalves from cold-seep habitats (2003)
    Inter Research
    In:  Marine Ecology Progress Series, 249 . pp. 39-51.
    Details
    Publication Date: 2018-05-30
    Description: The phylogenetic relationship of sulphur-oxidising endosymbiotic bacteria from bivalves of the families Vesicomyidae (Calyptogena sp. C1, Calyptogena sp. C3), Solemyidae (Acharax sp.) and Thyasiridae (Conchocele sp.) from cold-seep habitats were determined by 16S rDNA nucleotide sequence analyses. The endosymbiotic bacteria form distinct groups within the gamma-Proteobacteria and are well separated from each other and from free-living sulphur-oxidising bacteria of the genera Beggiatoa, Halothiobacillus and Thiomicrospira. The endosymbiotic bacteria of Acharax sp. from cold seeps off Oregon, Indonesia and Pakistan have sequences highly similar to each other but quite distinct from other thiotrophic endosymbionts. This includes endosymbionts from Solemya spp., to which they are distantly related. Symbiotic bacteria of Conchocele sp. from a cold seep in the Sea of Okhotsk are similar to those of Bathymodiolus thermophilus and related species, as shown by their overall sequence similarity and by signature sequences. The endosymbiotic bacteria of Calyptogena spp. from cold seeps off Oregon and Pakistan are closely related to those of other vesicomyids. Endosymbiont species found off Oregon corresponded to 2 different clusters of Calyptogena spp. symbionts in the same samples. The results corroborate the hypothesis of a monophyletic origin of the symbionts in vesicomyid clams, and support the existence of deeply branching groups in solemyid symbionts and of divergent lines and distribution for thyasirid symbionts. The results also indicate that certain symbiont species cluster according to the depth distribution of their hosts, and that in consequence host species together with their symbionts may have undergone depth-specific adaptation and evolution.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.3354/meps249039
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  • 6
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    Estimates of methane output from mud extrusions at the erosive convergent margin off Costa Rica (2006)
    Elsevier
    In:  Marine Geology, 225 . pp. 129-144.
    Details
    Publication Date: 2019-09-23
    Description: Four mud extrusions were investigated along the erosive subduction zone off Costa Rica. Active fluid seepage from these structures is indicated by chemosynthetic communities, authigenic carbonates and methane plumes in the water column. We estimate the methane output from the individual mud extrusions using two independent approaches. The first is based on the amount of CH4 that becomes anaerobically oxidized in the sediment beneath areas covered by chemosynthetic communities, which ranges from 104 to 105 mol yr− 1. The remaining portion of CH4, which is released into the ocean, has been estimated to be 102–104 mol yr− 1 per mud extrusion. The second approach estimates the amount of CH4 discharging into the water column based on measurements of the near-bottom methane distribution and current velocities. This approach yields estimates between 104–105 mol yr−1. The discrepancy of the amount of CH4 emitted into the bottom water derived from the two approaches hints to methane seepage that cannot be accounted for by faunal growth, e.g. focused fluid emission through channels in sediments and fractures in carbonates. Extrapolated over the 48 mud extrusions discovered off Costa Rica, we estimate a CH4 output of 20·106 mol yr− 1 from mud extrusions along this 350 km long section of the continental margin. These estimates of methane emissions at an erosional continental margin are considerably lower than those reported from mud extrusion at accretionary and passive margins. Almost half of the continental margins are described as non-accretionary. Assuming that the moderate emission of methane at the mud extrusions off Costa Rica are typical for this kind of setting, then global estimates of methane emissions from submarine mud extrusions, which are based on data of mud extrusions located at accretionary and passive continental margins, appear to be significantly too high.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.margeo.2005.09.007
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  • 7
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    Salt tectonics and mud volcanism in the Latakia and Cyprus Basins, eastern Mediterranean (2009)
    Elsevier
    In:  Tectonophysics, 470 (1/2). pp. 173-182.
    Details
    Publication Date: 2018-01-05
    Description: Salt tectonics and mud volcanism in the Latakia and Cyprus Basin, eastern Mediterranean, is investigated by means of swath sounding, reflection seismics and side-scan data as well as by camera and video sledge observations. Both basins are located east of Cyprus and are associated with the collision front between the African and Anatolian plate. The Pliocene–Quaternary sediment succession is underlain by up to 1 km thick Messinian evaporites. Both thick-skinned plate tectonic and thin-skinned salt tectonic control fluid dynamics and associated mud volcanism in the Latakia and Cyprus Basin as well as at the Troodos Latacia Culmination, which separates both basins. An end-member model is proposed which explains the presence of elongated topographic highs and trenches along the Troodos Larnaca Culmination and south of it by gravity gliding of the Messinian evaporites and associated fluid migration. Thin-skinned extension in the Troodos Larnaca Culmination and boudinage, respectively, facilitate fluid flow through and out of the evaporites. The fluid or mud flow dissolutes the salt layer and creates elongated trenches. Mud intrudes into the Pliocene–Quaternary sediments above the trenches. Consequently, the overburden is thickened and forms morphological ridges. South of the culmination the evaporites and overburden are folded due to thin-skinned shortening of the evaporites. In one instance fluid extrusion out of the evaporites is inferred from seismic data interpretation. The outflow caused a volume reduction and collapse of the evaporites. Mud volcanoes and fold anticlines align above deep-rooted transpressional fault systems which are associated with the African–Anatolian collision zone. The faults may act as conduits for rising fluids. In the western part of the survey area, where the Cyprus Arc strikes almost West–East and the collision occurred more frontal and stress was highest, mud volcanoes emerged. Further to the east, where the Cyprus Arc runs SW–NE and sinistral strike-slip has been proposed, fold anticlines evolved. Particular mud volcanoes and folds emerged prior to the deposition of the Messinian evaporites. The undisturbed upper Pleistocene sequences as well as the absence of significant mud outflow on the seafloor strongly suggest that the main fluid dynamic ceased.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.tecto.2008.08.019
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  • 8
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    Macrofaunal community structure and sulfide flux at gas hydrate deposits from the Cascadia convergent margin, NE Pacific (2002)
    Inter Research
    In:  Marine Ecology Progress Series, 231 . pp. 121-138.
    Details
    Publication Date: 2019-09-23
    Description: Gas hydrates occur at the sediment surface on the southern summit of Hydrate Ridge, Cascadia convergent margin. The hydrates are found in mounds several meters in diameter and up to 2 m high, and are covered by sediment and mats of the filamentous sulfur-oxidizing bacteria Beggiatoa. The mounds are surrounded by vesicomyid clams (Calyptogena pacifica, C. kilmeri), which in turn are encircled by solemyid bivalves (Acharax sp.). The zonation pattern of 3 species (Calyptogena spp. and Acharax sp., which harbor chemoautotrophic bacteria in their gills, and the chemoautotrophic Beggiatoa), is also reflected in a change in the entire community structure. Beggiatoa, Calyptogena spp. and Acharax sp. are shown to be characteristic species for the different communities. The Beggiatoa community directly overlaying the gas hydrates consists of seep endemic species in high densities: gastropods (Provanna laevis, P. lomana, Pyropelta corymba, Hyalogyrina sp. nov.), bivalves (Nuculana sp. nov.) and polychaetes (Ampharetidae, Polynoidae, Dorvilleidae). Based on pooled samples, the rarefaction curves show a decrease in species diversity in the Beggiatoa and Calyptogena communities. The hydrogen sulfide gradients in the porewater of sediments below the different communities dominated by either Beggiatoa, Calyptogena spp. or Acharax sp. vary by 3 orders of magnitude. The diffusive sulfide flux based on the measured sulfide concentration gradients is highest in Beggiatoa sp. communities (23 ± 13 mol m-2 yr-1), slightly less in Calyptogena communities (6.6 ± 2.4 mol m-2 yr-1), and low in Acharax communities (0.05 ± 0.05 mol m-2 yr-1). The difference in the sulfide environment is a factor influencing the distribution patterns of the chemoautotrophy-dependant and heterotrophic species at the deep-sea sediments containing gas hydrate.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.3354/meps231121
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  • 9
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    The physicochemical habitat of Sclerolinum sp., at Hook Ridge hydrothermal vent, Bransfield Strait, Antarctica (2005)
    ASLO (Association for the Sciences of Limnology and Oceanography)
    In:  Limnology and Oceanography, 50 (2). pp. 598-606.
    Details
    Publication Date: 2019-09-23
    Description: At Hook Ridge hydrothermal vent, a new species of Sclerolinum (Monilifera, Siboglinidae) was found at a water depth of 1,045 m. On the basis of investigations of multicores and gravity cores, the species habitat is characterized. Sclerolinum does not occur in sediments that are most strongly influenced by hydrothermal fluids, probably because of high temperature (up to 49°C) and precipitation of siliceous crusts. About 800 individuals m-2 occur in sediments that are only weakly exposed to hydrothermal flow and have the following characteristics: 20°C (15 cm sediment depth) to 21.5°C (bottom water), 18-40 cm yr-1 advection rates, pH 5.5, 〈25 µmol L-1 methane, 〈170 µmol L-1 sulfide, and 〈0.0054 mol m-2 yr-1 sulfide flux. Comparison with geochemical data from other reducing sediments indicates that the two groups of Siboglinidae, Monilifera and Frenulata, occur in sediments with low sulfide concentration and flux. In contrast, sulfurbased chemosynthetic organisms that typically occur at hydrothermal vents and cold seeps (e.g., Vestimentifera, vesicomyid clams, and bacterial mats) occur in sediments with higher sulfide availability; threshold values are around 500 µmol L-1 sulfide and 0.1 mol m-2 yr-1 sulfide fluxes. We did not find typical hydrothermal vent species at Hook Ridge hydrothermal vent, which might be explained by the unfavorable physicochemical habitat: At sites inhabited by Sclerolinum, sulfide availability appears to be too low, whereas at sites with higher sulfide availability, the temperatures might be too high, siliceous crust precipitation could preclude their occurrence, or both.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.4319/lo.2005.50.2.0598
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  • 10
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    Vodyanitskii mud volcano, Sorokin trough, Black Sea: geological characterization and quantification of gas bubble streams (2009)
    Elsevier
    In:  Marine and Petroleum Geology, 26 (9). pp. 1799-1811.
    Details
    Publication Date: 2019-09-23
    Description: Vodyanitskii mud volcano is located at a depth of about 2070 m in the Sorokin Trough, Black sea. It is a 500-m wide and 20-m high cone surrounded by a depression, which is typical of many mud volcanoes in the Black Sea. 75 kHz sidescan sonar show different generations of mud flows that include mud breccia, authigenic carbonates, and gas hydrates that were sampled by gravity coring. The fluids that flow through or erupt with the mud are enriched in chloride (up to similar to 650 mmol L-1 at similar to 150-cm sediment depth) suggesting a deep source, which is similar to the fluids of the close-by Dvurechenskii mud volcano. Direct observation with the remotely operated vehicle QUEST revealed gas bubbles emanating at two distinct sites at the crest of the mud volcano, which confirms earlier observations of bubble-induced hydroacoustic anomalies in echosounder records. The sediments at the main bubble emission site show a thermal anomaly with temperatures at similar to 60 cm sediment depth that were 0.9 degrees C warmer than the bottom water. Chemical and isotopic analyses of the emanated gas revealed that it consisted primarily of methane (99.8%) and was of microbial origin (delta D-CH4 = -170.8 parts per thousand (SMOW), delta C-13-CH4 = -61.0 parts per thousand (V-PDB), delta C-13-C2H6 = -44.0 parts per thousand (V-PDB)). The gas flux was estimated using the video observations of the ROV. Assuming that the flux is constant with time, about 0.9 +/- 0.5 x 106 mol of methane is released every year. This value is of the same order-of-magnitude as reported fluxes of dissolved methane released with pore water at other mud volcanoes. This suggests that bubble emanation is a significant pathway transporting methane from the sediments into the water column. (C) 2009 Elsevier Ltd. All rights reserved.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.marpetgeo.2009.01.010
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