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  • 1
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging of the Lake Agassiz–Lake Winnipeg transition (1998)
    Springer
    Journal of paleolimnology 19 (1998), S. 255-264 
    Details
    ISSN: 1573-0417
    Keywords: Lake Winnipeg ; magnetic resonance ; MRI ; SPRITE ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract As part of the Geologic Survey of Canada (GSC) Lake Winnipeg Study, we have successfully imaged the Lake Agassiz to Lake Winnipeg transition in Section 4 of Core Namao 94-900-122a (i.e., from 313 cm to 465 cm), using a newly-developed magnetic resonance imaging (MRI) technique called SPRITE (Single-Point, Ramped Imaging with T1 Enhancement). Whole core, gamma-ray attenuation measurements have been used to calculate the bulk porosity of the sediment at 1 cm intervals for comparison with the SPRITE images. Image contrast and image intensities observed in the SPRITE images of Section 4 are related to local porosity and magnetic susceptibility variations. In general, regions of the core with low signal intensity contain high porosity and low magnetic susceptibility. The best contrast between sediment layers is observed from regions of the core with high magnetic susceptibility. High signal intensity is observed from regions with low porosity and/or high magnetic susceptibility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007921832589
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Three-dimensional distribution of gas hydrate beneath southern Hydrate Ridge: constraints from ODP Leg 204 (2004)
    Elsevier
    In:  Earth and Planetary Science Letters, 222 (3-4). pp. 845-862.
    Details
    Publication Date: 2015-11-25
    Description: Large uncertainties about the energy resource potential and role in global climate change of gas hydrates result from uncertainty about how much hydrate is contained in marine sediments. During Leg 204 of the Ocean Drilling Program (ODP) to the accretionary complex of the Cascadia subduction zone, we sampled the gas hydrate stability zone (GHSZ) from the seafloor to its base in contrasting geological settings defined by a 3D seismic survey. By integrating results from different methods, including several new techniques developed for Leg 204, we overcome the problem of spatial under-sampling inherent in robust methods traditionally used for estimating the hydrate content of cores and obtain a high-resolution, quantitative estimate of the total amount and spatial variability of gas hydrate in this structural system. We conclude that high gas hydrate content (30–40% of pore space or 20–26% of total volume) is restricted to the upper tens of meters below the seafloor near the summit of the structure, where vigorous fluid venting occurs. Elsewhere, the average gas hydrate content of the sediments in the gas hydrate stability zone is generally 〈2% of the pore space, although this estimate may increase by a factor of 2 when patchy zones of locally higher gas hydrate content are included in the calculation. These patchy zones are structurally and stratigraphically controlled, contain up to 20% hydrate in the pore space when averaged over zones ∼10 m thick, and may occur in up to ∼20% of the region imaged by 3D seismic data. This heterogeneous gas hydrate distribution is an important constraint on models of gas hydrate formation in marine sediments and the response of the sediments to tectonic and environmental change.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1016/j.epsl.2004.03.035
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    A 160,000-Year high-resolution record of quantity and composition of organic carbon in the Santa Barbara Basin (Site 893) (1995)
    In:  EPIC3Proceedings ODP, Scientific ResultsPart 2), 146, pp. 125-138
    Details
    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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    PAPER (OA)
  • 4
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    Drilling in the Amundsen Sea Embayment: Reconstructing West Antarctic Ice Sheet dynamics (IODP 784-Full proposal) (2012)
    In:  EPIC3IODP/ICDP Kolloquium der Deutschen Forschungsgemeinschaft, GEOMAR, Kiel, Germany, 2012-03-07-2012-03-09
    Details
    Publication Date: 2018-08-10
    Description: The West Antarctic Ice Sheet (WAIS), which is grounded below present sea level and, thus, is highly sensitive to climatic changes, is likely to have had a very dynamic history over the last several million years. Its collapse would result in a global sea-level rise of 3-5 m over present levels yet the world’s scientific community is not able to predict how it might behave in the future, nor is much known of how it has behaved in the past. The reconstruction and quantification of partial or complete WAIS collapses in the geological past are needed in order to provide necessary constraints for ice sheet models predicting future WAIS behaviour and its potential contributions to global sea-level rise. Large uncertainties exist regarding the chronology, extent, rates, and spatial and temporal variability of past advances and retreats of the WAIS across the continental shelves. These uncertainties are mainly due to the fundamental lack of data from drill core. A series of drill sites are proposed for the Amundsen Sea Embayment shelf where seismic data reveal oceanward dipping sedimentary sequences that span the time from the pre-glacial depositional phase to the youngest glacial periods. Our drilling strategy is to target a transect from the oldest sequences close to the bedrock-basin boundary in the south to the youngest sequences in the north of the western and eastern Amundsen Sea Embayment continental shelf. This transect will yield a detailed history of the glacial cycles in the Pine Island-Amundsen Sea region and allow correlations to the WAIS history known from the Ross Sea. In addition, deep-water sites on the continental rise of the embayment are selected for recovering continuous records of glacially transported sediments and the details of climatic and oceanographic changes throughout glacial-interglacial cycles.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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