| 1. |
- Samyn, Denis, et al.
(author)
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A simple and updated pneumatic method for uniaxial ice compression in the laboratory : experimental settings and creep test results on glacier ice
- 2011
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In: Journal of Glaciology. - 0022-1430 .- 1727-5652. ; 57:202, s. 337-344
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Journal article (peer-reviewed)abstract
- Creep tests provide invaluable data to better understand the physical properties of ice under various conditions. We describe here a simple, updated pneumatic apparatus for experimental studies of ice rheological properties. The apparatus is designed to perform two simultaneous compression creep tests either in a cold room or in atmospheric conditions when coupled to an external cooling circulator. We present results from calibration tests of the apparatus and provide new data from creep tests performed on temperate glacier ice samples. These calibration and creep results show that the apparatus is able to provide fast and reliable mechanical ice characterization. The secondary creep rates measured in this study range between 1.59 x 10(-8) s(-1) (at 0.21 MPa) and 4.38 x 10(-7) s(-1) (at 0.71 MPa) at -10 degrees C for quasi-isotropic ice, which is consistent with former standard published data. The corresponding mean parameter, A, is 5.20 x 10(-16) s(-1) kPa(-3), which also compares well with the range of reported other studies.
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| 2. |
- Samyn, Denis, et al.
(author)
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Rotating micro-structures in Antarctic cold basal ice : implications for glacier flow and its interpretation
- 2010
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In: International journal of earth sciences. - : Springer Science and Business Media LLC. - 1437-3254 .- 1437-3262. ; 99:8, s. 1849-1857
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Journal article (peer-reviewed)abstract
- Structural analyses were conducted in the basal zone of an Antarctic glacier The studied basal ice sequence was retrieved from a 20-m-long subglacial tunnel dug at the margin of the glacier and is at the temperature of -17 degrees C For the first time, rotating clast systems embedded within debris-rich ice were thin-sectioned using specially designed cutting techniques The observed structures reflect the occurrence of pervasive shearing at the base of the glacier, and can be used as shear sense indicators In addition, some of these structures provide evidence for the presence of thin liquid films at the time of formation despite the marked freezing temperature of the ice It is showed here that cautious analysis of deformation structures present in debris-bearing ice may bring insights not only into the flow dynamics of the embedding matrix, but also Into the behaviour of the interstitial fluid network at the base of cold glaciers and ice sheets.
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| 3. |
- Vega, Carmen P., et al.
(author)
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First Ice Core Records of NO3- Stable Isotopes from Lomonosovfonna, Svalbard
- 2015
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In: Journal of Geophysical Research - Atmospheres. - 2169-897X .- 2169-8996. ; 120:1, s. 313-330
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Journal article (peer-reviewed)abstract
- Samples from two ice cores drilled at Lomonosovfonna, Svalbard, covering the period 1957-2009, and 1650-1995, respectively, were analyzed for NO(3)(-)concentrations, and NO3- stable isotopes (N-15 and O-18). Post-1950 N-15 has an average of (-6.91.9), which is lower than the isotopic signal known for Summit, Greenland but agrees with values observed in recent Svalbard snow and aerosol. Pre-1900 N-15 has an average of (4.21.6)parts per thousand suggesting that natural sources, enriched in the N-15 isotope, dominated before industrialization. The post-1950 O-18 average of (75.1 +/- 4.1)parts per thousand agrees with data from low and polar latitudes, suggesting similar atmospheric NOy (NOy=NO+NO2+HNO3) processing pathways. The combination of anthropogenic source N-15 and transport isotope effect was estimated as -29.1 parts per thousand for the last 60years. This value is below the usual range of NOx (NOx=NO+NO2) anthropogenic sources which is likely the result of a transport isotope effect of -32 parts per thousand. We suggest that the N-15 recorded at Lomonosovfonna is influenced mainly by fossil fuel combustion, soil emissions, and forest fires; the first and second being responsible for the marked decrease in N-15 observed in the post-1950s record with soil emissions being associated to the decreasing trend in N-15 observed up to present time, and the third being responsible for the sharp increase of N-15 around 2000.
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