GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Online Resource
    Online Resource
    Fluid Migration at Opouawe Bank, offshore New Zealand (2016)
    Kiel
    Details Availability
    Keywords: Hochschulschrift ; Neuseeland ; Kontinentalrand ; Fluid ; Migration
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource
    URL: http://nbn-resolving.de/urn:nbn:de:gbv:8-diss-190179
    URL: http://d-nb.info/1107010810/34
    URL: http://macau.uni-kiel.de/receive/dissertation_diss_00019017
    URN: urn:nbn:de:gbv:8-diss-190179
    DDC: 550
    Language: English
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GEOMAR CATALOGUE
    Link to Library Catalog
    get availability status
  • 2
    Electronic Resource
    Electronic Resource
    Reflectance anisotropy investigation of the metalorganic chemical-vapor deposition of III-V heterojunctions (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 1389-1398 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using reflectance anisotropy (RA), we investigated in situ the metalorganic chemical-vapor deposition of a number of III-V heterojunctions. Each type of heterojunction exhibits a characteristic RA record as a function of time, depending on the film composition, growth rate, and interface quality, as well as the light wavelength used. Signal changes occurring over different time scales are related to a number of different contributions to the optical anisotropy of the material. Changes during the first 5–10 s are due to the optical anisotropy of both the surface and heterointerface. Over a time scale of several minutes, the signal exhibits damped sinusoidal behavior; a model is proposed to account for these changes, taking into account the interference of light in the growing layer. Finally, the steady-state signal obtained after many minutes is indicative of the difference in surface optical anisotropy between the epilayer and substrate. Practical applications of RA, including heterojunction optimization, superlattice monitoring, and reactor geometry improvements, are also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347278
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    In situ investigation of InAs metalorganic chemical vapor deposition growth using reflectance anisotropy (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 3364-3369 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using reflectance anisotropy, we have investigated InAs metalorganic chemical vapor deposition under optimal growth conditions. The measured optical anisotropy of the growing surface is significantly different from that of the nongrowing, AsH3-stabilized surface. This difference δ becomes more pronounced at low V/III gas flow ratios and low temperatures. The value of δ also depends on the light energy, reaching a maximum in the range of 2.30–2.38 eV. In addition, we show that it is possible to monitor effects of the reactor on the growth, namely transient flow perturbations on the growing surface due to the switching of gas flows.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346365
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    facet.materialart.
    Unknown
    Marine-controlled source electromagnetic study of methane seeps and gas hydrates at Opouawe Bank, Hikurangi Margin, New Zealand (2017)
    AGU (American Geophysical Union) | Wiley
    In:  Journal of Geophysical Research: Solid Earth, 122 (5). pp. 3334-3350.
    Details
    Publication Date: 2020-02-06
    Description: Marine controlled source electromagnetic (CSEM) data have been collected to investigate methane seep sites and associated gas hydrate deposits at Opouawe Bank on the southern tip of the Hikurangi Margin, New Zealand. The bank is located in about 1000 m water depth within the gas hydrate stability field. The seep sites are characterized by active venting and typical methane seep fauna accompanied with patchy carbonate outcrops at the seafloor. Below the seeps, gas migration pathways reach from below the bottom-simulating reflector (at around 380 m sediment depth) toward the seafloor, indicating free gas transport into the shallow hydrate stability field. The CSEM data have been acquired with a seafloor-towed, electric multi-dipole system measuring the inline component of the electric field. CSEM data from three profiles have been analyzed by using 1-D and 2-D inversion techniques. High-resolution 2-D and 3-D multichannel seismic data have been collected in the same area. The electrical resistivity models show several zones of highly anomalous resistivities (〉50 Ωm) which correlate with high amplitude reflections located on top of narrow vertical gas conduits, indicating the coexistence of free gas and gas hydrates within the hydrate stability zone. Away from the seeps the CSEM models show normal background resistivities between ~1 and 2 Ωm. Archie's law has been applied to estimate gas/gas hydrate saturations below the seeps. At intermediate depths between 50 and 200 m below seafloor, saturations are between 40 and 80% and gas hydrate may be the dominating pore filling constituent. At shallow depths from 10 m to the seafloor, free gas dominates as seismic data and gas plumes suggest.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1002/2016JB013702
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
    facet.materialart.
    Unknown
    Giant depressions on the Chatham Rise offshore New Zealand – Morphology, structure and possible relation to fluid expulsion and bottom currents (2018)
    Elsevier
    In:  Marine Geology, 399 . pp. 158-169.
    Details
    Publication Date: 2021-02-08
    Description: Highlights • Large seafloor depressions with diameters of up 10 km across have been mapped on the southern Chatham Rise, New Zealand. • Seismic reflection data show scarce indications for vertical fluid flow but no clear link between fluid flow and depressions. • Methane gas or methane hydrates appear to be absent on the southern Chatham Rise. • Seismic evidence suggests that vertical fluid flow was likely fuelled by polygonal faulting and silica diagenesis • The depressions are the results of erosion and sediment drift deposition of bottom currents associated with the Subtropical Front. Abstract Several giant seafloor depressions were investigated on the Chatham Rise offshore New Zealand using mainly bathymetric and seismic data, supplemented by sediment cores and reported porewater geochemistry data. The depressions have diameters of up to 11 km and occur on the southern flank of the Chatham Rise in water depths between 600 and 900 m, i.e. roughly underneath the location of the strongest thermal gradients of the Subtropical Front (STF) and characterized by eastward flowing currents. With up to 150 m of relief the depressions cut into post-Miocene deposits. Some of the depressions are partially filled with drift deposits that have similar seismic characteristics as the surrounding sediments and consist of alternations of silty muds and silts. Seismic profiles also show completely filled depressions that no longer have a bathymetric expression. Despite several pipe structures indicating vertical fluid flow, neither active fluid seepage nor indications for past fluid seepage are present at the seafloor of the Chatham Rise. Also, both pore water geochemistry and geophysical data do not show indications for an existing or past gas hydrate system in the area. Instead, seismic data suggest widespread polygonal faulting and the presence of silica diagenetic fronts. The release of mineral-bound water during silica diagenesis or fluid expulsion during sediment compaction can explain the presence of vertical fluid flow features but not the giant depressions themselves. Instead, the depressions are interpreted as the result of scouring by strong bottom currents for which fluid venting may have created the nucleation points.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1016/j.margeo.2018.02.011
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
    facet.materialart.
    Unknown
    Elongate fluid flow structures: Stress control on gas migration at Opouawe Bank, New Zealand (2018)
    Elsevier
    In:  Marine and Petroleum Geology, 92 . pp. 913-931.
    Details
    Publication Date: 2021-02-08
    Description: Highlights • Elongated fault structures are conduits for focused fluid flow. • Gas migration occurs only along a sub-set of faults across Opouawe bank. • Stress state deduced from 3D fault structures appears partially stratigraphically controlled. Abstract High-resolution 2D and 3D seismic data from Opouawe Bank, an accretionary ridge on the Hikurangi subduction margin off New Zealand, show evidence for exceptional gas migration pathways linked to the stress regime of the ridge. Although the ridge has formed by thrusting and folding in response to a sub-horizontal principal compressive stress (σ1), it is clear that local stress conditions related to uplift and extension around the apex of folding (i.e. sub-vertical σ1) are controlling shallow fluid flow. The most conspicuous structural features are parallel and horizontally-elongated extensional fractures that are perpendicular to the ridge axis. At shallower depth near the seafloor, extensional fractures evolve into more concentric structures which ultimately reach the seafloor where they terminate at gas seeps. In addition to the ridge-perpendicular extensional fractures, we also observe both ridge-perpendicular and ridge-parallel normal faults. This indicates that both longitudinal- and ridge-perpendicular extension have occurred in the past. The deepest stratigraphic unit that we image has undergone significant folding and is affected by both sets of normal faults. Shallower stratigraphic units are less deformed and only host the ridge-parallel normal faults, indicating that longitudinal extension was limited to an older phase of ridge evolution. Present-day gas migration has exploited the fabric from longitudinal extension at depth. As the gas ascends to shallower units it ‘self-generates’ its flow pathways through the more concentric structures near the seafloor. This shows that gas migration can evolve from being dependent on inherited tectonic structures at depth, to becoming self-propagating closer to the seafloor.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1016/j.marpetgeo.2018.03.029
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
    facet.materialart.
    Unknown
    Free gas distribution and basal shear zone development in a subaqueous landslide – Insight from 3D seismic imaging of the Tuaheni Landslide Complex, New Zealand (2018)
    Elsevier
    In:  Earth and Planetary Science Letters, 502 . pp. 231-243.
    Details
    Publication Date: 2021-05-10
    Description: Highlights • 3D seismic imaging of an entire landslide complex. • Shallow gas accumulation within and underneath Tuaheni Landslide Complex. • Imaging of a basal shear zone within a subaqueous landslide complex. Abstract The Hikurangi margin is an active continental margin east of New Zealand's North Island. It is well recognized as a seismically active zone and is known for the occurrence of free gas and gas hydrates within the shallow sediments. A variety of subaqueous landslides can be observed at the margin, including the Tuaheni Landslide Complex off Poverty Bay. This slide complex has been interpreted previously as a slowly creeping landform, as its morphology and internal deformation is comparable to terrestrial earthflows and rock glaciers. In 2014, we acquired a high-resolution 3D seismic volume covering major parts of the Tuaheni South landslide. The 3D data show a variety of fluid migration indicators, free gas accumulations and manifestations of the base of gas hydrate stability in the pre-slide sedimentary units and the lower unit of the landslide system. The data also show that the landslide system is composed of an upper and lower unit that are separated by an intra-debris negative-polarity reflection. Free gas accumulations directly beneath the landslide units suggest that the debris acts as a boundary for rising fluids and only few migration pathways to the intra-debris reflector are observed in the distal parts of the landslide. Deformation within the landslide's debris is focused in the upper landslide unit, and we interpret the intra-debris reflector as a basal shear zone or ‘glide plane’ upon which the debris has been remobilized. The origin of the intra-debris reflector is unclear, but we suggest it could be a relatively coarse-grained horizon that would be prone to fluid flow focusing and the development of excess fluid pressure. Our seismic study provides one of the most detailed examples of a subaqueous landslide system and reveals insights into the fluid flow system and potential basal shear zone development of the Tuaheni Landslide Complex.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1016/j.epsl.2018.09.002
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
    facet.materialart.
    Unknown
    Paleo-Fluid Expulsion Influencing Contouritic Drift Formation on the Chatham Rise, New Zealand (2018)
    Wiley
    In:  Basin Research, 30 (1). pp. 5-19.
    Details
    Publication Date: 2021-02-08
    Description: The Chatham Rise is located offshore of New Zealand's South Island. Vast areas of the Chatham Rise are covered in circular to elliptical seafloor depressions that appear to be forming through a bathymetrically controlled mechanism, as seafloor depressions 2-5 km in diameter are found in water depths of 800-1100 m. High resolution P-Cable 3D seismic data were acquired in 2013 across one of these depressions. The seafloor depression is interpreted as a mounded contourite. Our data reveal several smaller buried depressions (〈20-650 m diameter) beneath the mounded contourite that we interpret as paleo-pockmarks. These pockmarks are underlain by a complex polygonal fault system that deforms strata and an unusual conical feature. We interpret the conical feature as a sediment remobilization structure based on the presence of stratified reflections within the feature, RMS amplitude values and lack of velocity anomaly that would indicate a non-sedimentary origin. The sediment remobilization structure, polygonal faults and paleo-depressions are indicators of past subsurface fluid flow. We hypothesize that the pockmarks provided the necessary topographic roughness for formation of the mounded contourites thus linking fluid expulsion and deposition of contouritic drifts.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1111/bre.12237
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
    facet.materialart.
    Unknown
    On the origin of multiple BSRs in the Danube deep-sea fan, Black Sea (2017)
    Elsevier
    In:  Earth and Planetary Science Letters, 462 . pp. 15-25.
    Details
    Publication Date: 2020-02-06
    Description: Highlights • A stack of four BSRs were identified in levee deposits of the Danube deep-sea fan. • The multiple BSRs are not caused by overpressure compartments. • The multiple BSRs reflect stages of stable sealevel lowstands during glacial times. • Gas underneath the previous GHSZ does not start to migrate for thousands of years. Abstract High-resolution 2D seismic data reveal the character and distribution of up to four stacked bottom simulating reflectors (BSR) within the channel-levee systems of the Danube deep-sea fan. The theoretical base of the gas hydrate stability zone (GHSZ) calculated from regional geothermal gradients and salinity data is in agreement with the shallowest BSR. For the deeper BSRs, BSR formation due to overpressure compartments can be excluded because the necessary gas column would exceed the vertical distance between two overlying BSRs. We show instead that the deeper BSRs are likely paleo BSRs caused by a change in pressure and temperature conditions during different limnic phases of the Black Sea. This is supported by the observation that the BSRs correspond to paleo seafloor horizons located in a layer between a buried channel-levee system and the levee deposits of the Danube channel. The good match of the observed BSRs and the BSRs predicted from deposition of these sediment layers indicates that the multiple BSRs reflect stages of stable sealevel lowstands possibly during glacial times. The observation of sharp BSRs several 10,000 of years but possibly up to 300,000 yr after they have left the GHSZ demonstrates that either hydrate dissociation does not take place within this time frame or that only small amounts of gas are released that can be transported by diffusion. The gas underneath the previous GHSZ does not start to migrate for several thousands of years.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
    DOI: 10.1016/j.epsl.2017.01.006
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
    facet.materialart.
    Unknown
    Gas-controlled seafloor doming (2015)
    GSA (Geological Society of America)
    In:  Geology, 43 (7). pp. 571-574.
    Details
    Publication Date: 2019-10-24
    Description: The upward migration of gas through marine sediments typically manifests itself as gas chimneys or pipes in seismic images and can lead to the formation of cold seeps. Gas seepage is often linked to morphological features like seabed domes, pockmarks, and carbonate build-ups. In this context, sediment doming is discussed to be a precursor of pockmark formation. Here, we present parametric echosounder, sidescan sonar, and two-dimensional seismic data from Opouawe Bank, offshore New Zealand, providing field evidence for sediment doming. Geomechanical quantification of the stresses required for doming show that the calculated gas column heights are geologically feasible and consistent with the observed geophysical data. The progression from channeled gas flow to gas trapping results in overpressure build-up in the shallow sediment. Our results suggest that by breaching of domed seafloor sediments a new seep site can develop, but contrary to ongoing discussion this does not necessarily lead to the formation of pockmarks.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1130/G36596.1
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...