scholarly journals Study of an ice core to the bedrock in the accumulation zone of an Alpine glacier

1976 ◽  
Vol 17 (75) ◽  
pp. 13-28 ◽  
Author(s):  
M. Vallon ◽  
J.-R. Petit ◽  
B. Fabre
Keyword(s):  
Water Content ◽  
Ice Core ◽  
Ice Crystal ◽  
Vertical Orientation ◽  
Axis Orientation ◽  
Alpine Glacier ◽  
Small Crystals ◽  
Average Water ◽  
Intermediate Size ◽  
Average Size

AbstractA water table appearing every summer where the ice begins, at a gerpth of approximately 30 m, accelerates the transformation of firn into ice during the summer (80% of the ice formed every year appears in less than 2 months). The ice formed in this way contains from 0 to 0.6% water. The average water content increases gradually with the gerpth because of the heat of gerformation. But, near bedrock, between 180 and 187 m, the permeability of the blue ice is such that the water content drops (0.3% as compared to 1.3% between 160 and 180 m).From a gerpth of 33 m, a foliation of sedimentary origin gradually gervelops in the ice. Its dip increases regularly to a gerpth of 145 m. At 145 m it jumps sudgernly freom 20° to 40°, then at 170 m freom 40° to 65°, which can be explained by old modifications in the bergschrund. This foliation disappears near bedrock (180-187 m), where there are no bubbles in the ice.The average size of an ice crystal increases slowly in the firn, shows seasonal fluctuations between 30 and 50 m, then jumps freom a diameter of 1 or 2 mm to 10 or 20 mm between 50 and 80 m. Between 180 and 187 m, the ice is mager of large crystals (3-10 cm diameter; the figure, however, is probably inexact due to a recrystallization of the samples).The very strong sub-vertical orientation of the optic axes of the firn crystals disappears quickly, and freom 66 m on, in ice with large crystals, a fabric of multiple maxima appears (generally, 3 or 4 directions, forming a triangle or a rhombus). On the other hand, in the small crystals that form bands parallel to the plane of foliation, only one direction of preferential orientation can be seen, or two close to one another. Crystals of intermediate size (10 to 50 mm) generally have two directions of preferred orientation at an angle of approximately 50° to one another. No matter how big the crystals are, the angle between the most commonc-axis orientation and the vertical does not change freom 60 to 170 m gerpth.

scholarly journals Study of an Ice Core to the Bedrock in the Accumulation zone of an Alpine Glacier

1976 ◽  
Vol 17 (75) ◽  
pp. 13-28 ◽  
Author(s):  
M. Vallon ◽  
J.-R. Petit ◽  
B. Fabre
Keyword(s):  
Water Content ◽  
Ice Core ◽  
Ice Crystal ◽  
Vertical Orientation ◽  
Axis Orientation ◽  
Alpine Glacier ◽  
Small Crystals ◽  
Average Water ◽  
Intermediate Size ◽  
Average Size

AbstractA water table appearing every summer where the ice begins, at a gerpth of approximately 30 m, accelerates the transformation of firn into ice during the summer (80% of the ice formed every year appears in less than 2 months). The ice formed in this way contains from 0 to 0.6% water. The average water content increases gradually with the gerpth because of the heat of gerformation. But, near bedrock, between 180 and 187 m, the permeability of the blue ice is such that the water content drops (0.3% as compared to 1.3% between 160 and 180 m).From a gerpth of 33 m, a foliation of sedimentary origin gradually gervelops in the ice. Its dip increases regularly to a gerpth of 145 m. At 145 m it jumps sudgernly freom 20° to 40°, then at 170 m freom 40° to 65°, which can be explained by old modifications in the bergschrund. This foliation disappears near bedrock (180-187 m), where there are no bubbles in the ice.The average size of an ice crystal increases slowly in the firn, shows seasonal fluctuations between 30 and 50 m, then jumps freom a diameter of 1 or 2 mm to 10 or 20 mm between 50 and 80 m. Between 180 and 187 m, the ice is mager of large crystals (3-10 cm diameter; the figure, however, is probably inexact due to a recrystallization of the samples).The very strong sub-vertical orientation of the optic axes of the firn crystals disappears quickly, and freom 66 m on, in ice with large crystals, a fabric of multiple maxima appears (generally, 3 or 4 directions, forming a triangle or a rhombus). On the other hand, in the small crystals that form bands parallel to the plane of foliation, only one direction of preferential orientation can be seen, or two close to one another. Crystals of intermediate size (10 to 50 mm) generally have two directions of preferred orientation at an angle of approximately 50° to one another. No matter how big the crystals are, the angle between the most common c-axis orientation and the vertical does not change freom 60 to 170 m gerpth.

scholarly journals Crystal Size and Orientation Patterns in the Wisconsin-Age Ice from Dye 3, Greenland

1988 ◽  
Vol 10 ◽  
pp. 109-115 ◽  
Author(s):  
C.C. Langway ◽  
H. Shoji ◽  
N. Azuma
Keyword(s):  
Crystal Size ◽  
Ice Core ◽  
Ice Crystal ◽  
Axis Orientation ◽  
Measuring Device ◽  
Thin Sections ◽  
Core Samples ◽  
Physical Measurements ◽  
Ice Crystal Size ◽  
Velocity Measuring

Crystal size and c-axis orientation patterns were measured on the Dye 3, Greenland, deep ice core in order to investigate time-dependent changes or alterations in the physical character of the core as a function of time after recovery. The physical measurements were expanded to include depth intervals not previously studied in the field. The recent study focused on core samples located between 1786 m and the bottom of the ice sheet at 2037 m.Manual c-axis measurements were made on 23 new thin sections using a Rigsby-type universal stage. A new semi-automatic ultrasonic wave-velocity measuring device was developed in order to compare the results with the earlier manual measurements and to study an additional 114 ice-core samples in the Wisconsin-age ice. Crystal-size measurements were made on specimen surfaces by inducing evaporation grooves at crystal boundaries and measuring linear intercepts. The ultrasonically measured test samples were subsequently cleaned and analyzed by ion chromatography in order to measure impurity concentration levels of Cl−, NO3− and SO42− and study their effects on crystal growth and c-axis orientation.

scholarly journals Complete determination of ice crystal orientation using Laue X-ray diffraction method

2011 ◽  
Vol 57 (201) ◽  
pp. 103-110 ◽  
Author(s):  
Atsushi Miyamoto ◽  
Ilka Weikusat ◽  
Takeo Hondoh
Keyword(s):  
Crystal Orientation ◽  
Ice Core ◽  
Ice Sheets ◽  
Diffraction Method ◽  
Ice Cores ◽  
Ice Crystals ◽  
Ice Crystal ◽  
X Ray Diffraction ◽  
Axis Orientation ◽  
X Ray

AbstractIce crystal orientation fabric data from ice cores contain important information concerning the internal structure and the flow behaviour of ice sheets. When ice cores are recovered from the Antarctic and Greenland ice sheets, crystal orientation measurements are performed immediately to obtain fundamental physical property information. In the past, we have measured the c-axis orientation of ice crystals by a manual optical method using a universal stage. This method is very time-consuming, involving tedious work in a cold laboratory. Recently, automated systems have been developed that enable measurement of c-axis orientation, grain size and other microstructures. However, in order to detect the full crystal orientation of an ice crystal, we also need information on its a-axis orientation. A variety of other crystal orientation measurement methods have previously been discussed, but some shortcomings for ice-core studies cannot be neglected. We have developed a crystal-orientation analysing device using the Laue X-ray diffraction method. As this device can measure the orientations of all crystal axes with high accuracy, it is possible to obtain new microstructure information on natural ice crystals. For the first time, we are able to quantify very low subgrain misorientation angles in polar ice-core samples, allowing us to investigate micro-deformation features of individual crystals. Here we discuss the analysis process, which is customized to measure standard ice thin sections, and show preliminary results.

scholarly journals Seasonal variability in ice crystal properties at NorthGRIP: a case study around 301 m depth

2003 ◽  
Vol 37 ◽  
pp. 119-122 ◽  
Author(s):  
Anders Svensson ◽  
Pauli Baadsager ◽  
Asbjørn Persson ◽  
Christine Schøtt Hvidberg ◽  
Marie-Louise Siggaard-Andersen
Keyword(s):  
Seasonal Variability ◽  
Ice Core ◽  
Ice Crystal ◽  
Axis Orientation ◽  
Annual Cycles ◽  
Average Value ◽  
The North ◽  
Chemical Impurities ◽  
Crystal Properties

AbstractThe aim of this case study is to quantify the seasonal variability in crystal properties and to discuss the reason for the variability. A continuous 1.10 m long vertical thin-section profile covering approximately five annual cycles has been obtained from the North Greenland Icecore Project (NorthGRIP) ice core at around 301 m depth. The crystal outline and the c-axis orientation of more than 13000 crystals in the profile have been measured on a new Australian automated ice-crystal analyzer. In 2.5 cm resolution we observe a strong seasonal variability in crystal areas of >30%deviation from the average value of 6.7 mm2. Each year, a band of smaller crystals is observed in ice deposited during spring. The area distribution function is found to be close to a lognormal distribution. The crystal areas are compared to the concentration of chemical impurities in the ice; at a 5 cm resolution, the best correlation is found with the concentration of Ca2+. Our results show no seasonal variability of the average c-axis orientation of ice crystals.

scholarly journals Textures and fabrics in the Dome F (Antarctica) ice core

1999 ◽  
Vol 29 ◽  
pp. 163-168 ◽  
Author(s):  
N. Azuma ◽  
Y. Wang ◽  
K. Mori ◽  
H. Narita ◽  
T. Hondoh ◽  
...  
Keyword(s):  
Crystal Size ◽  
Ice Core ◽  
Clear Correlation ◽  
Crystal Shape ◽  
Ice Crystal ◽  
Axis Orientation ◽  
Thin Sections ◽  
Crystal Axis ◽  
Orientation Pattern ◽  
Comprehensive Study

AbstractA comprehensive study of ice-crystal fabrics and textures was conducted on the Dome F (Antarctica) ice core. Crystal ,-axis orientations, crystal sizes and crystal shape were measured on thin sections with an automatic ice-fabric analyzer. The general feature of textural and fabric development through a 2500 m long core was obtained by a 20 m interval study. Crystal size steadily increases with depth except for depths of about 500,1800, 2000, 2200 and 2300 m, at which depths crystal size decreases suddenly. There is a clear correlation between crystal-size and ´18O values. Crystals tend to elongate horizontally with depth, and the aspect ratio (long axis vs short axis of a grain) increases twofold at 1600 m depth and fluctuates below that depth. The .-axis orientation fabrics gradually change with depth from a random orientation pattern near the surface to a strong vertical single maximum at 2500 m. These are very similar to those from the GRIP (Greenland) core The observations of crystal shape and the fabric measurements indicate that nucleation-recrystallization does not take place at Dome F.

scholarly journals Properties of GRIP ice crystals from around Greenland interstadial 3

2002 ◽  
Vol 35 ◽  
pp. 531-537 ◽  
Author(s):  
Kaj M. Hansen ◽  
Anders Svensson ◽  
Yun Wang ◽  
Jørgen Peder Steffensen
Keyword(s):  
Ice Core ◽  
Ice Crystal ◽  
Vertical Orientation ◽  
Thin Sections ◽  
Area Distribution ◽  
Before And After ◽  
Manual Methods ◽  
Log Normal ◽  
Log Normal Distribution ◽  
Automated Methods

AbstractIce-crystal textures (sizes and shapes) and fabrics (c-axis orientations) have been determined in 3 m of vertical thin sections from the Greenland Icecore Project (GRIP) ice core. the samples cover ice from before, during and after Greenland interstadial 3 (IS3) that occurred about 25 kyr BP. the texture of 60 000 crystals has been obtained from stacked digital images by semi-automated methods, and the fabric of 5000 selected crystals has been measured on the Automatic Ice Fabric Analyzer at the Alfred Wegener Institute, Bremerhaven. the area distribution function of the crystals is close to a log normal distribution, and the mean area is found to be 3.36 mm2 in ice from IS3, and 3.04 mm2 in ice from colder periods before and after IS3. the overall c-axis orientations show a strong single maximum with vertical orientation. These results agree well with earlier GRIP fabric studies obtained by manual methods. from comparisons of crystal areas with the concentrations of dust, Ca2+, SO42–, Cl– and NO3– in the ice we determine that NO3– correlates best with crystal areas. Crystals within clearly visible cloudy bands are significantly smaller than the surrounding crystals, and their c-axis orientations are less well confined than the average.

scholarly journals Crystal Size and Orientation Patterns in the Wisconsin-Age Ice from Dye 3, Greenland

1988 ◽  
Vol 10 ◽  
pp. 109-115 ◽  
Author(s):  
C.C. Langway ◽  
H. Shoji ◽  
N. Azuma
Keyword(s):  
Crystal Size ◽  
Ice Core ◽  
Ice Crystal ◽  
Axis Orientation ◽  
Measuring Device ◽  
Thin Sections ◽  
Core Samples ◽  
Physical Measurements ◽  
Ice Crystal Size ◽  
Velocity Measuring

Crystal size and c-axis orientation patterns were measured on the Dye 3, Greenland, deep ice core in order to investigate time-dependent changes or alterations in the physical character of the core as a function of time after recovery. The physical measurements were expanded to include depth intervals not previously studied in the field. The recent study focused on core samples located between 1786 m and the bottom of the ice sheet at 2037 m. Manual c-axis measurements were made on 23 new thin sections using a Rigsby-type universal stage. A new semi-automatic ultrasonic wave-velocity measuring device was developed in order to compare the results with the earlier manual measurements and to study an additional 114 ice-core samples in the Wisconsin-age ice. Crystal-size measurements were made on specimen surfaces by inducing evaporation grooves at crystal boundaries and measuring linear intercepts. The ultrasonically measured test samples were subsequently cleaned and analyzed by ion chromatography in order to measure impurity concentration levels of Cl−, NO3− and SO4 2− and study their effects on crystal growth and c-axis orientation.

KARAKTERISTIK ABON IKAN GABUS (Channa striata) DENGAN SUBTITUSI KLUWIH (Artocarpus camansi)

2018 ◽  
Vol 16 (2) ◽  
pp. 219-226
Author(s):  
Sri Rizqi Annisa ◽  
Dewi Larasati ◽  
Endang Bekti K
Keyword(s):  
Protein Content ◽  
Water Content ◽  
Analysis Of Variance ◽  
Fiber Content ◽  
Substitution Treatment ◽  
Fish Fillet ◽  
Organoleptic Test ◽  
Average Water ◽  
Channa Striata

The aim of this study was to determine the characterization of shredded mureel fish with kluwih substitution on water content, protein content, fiber content and organoleptic (preference for crispness and taste). This study uses a simple Randomized Complete Design (RCD) with the substitution treatment of kluwih and mureel fish, with the following ratio: S1 (240g: 60g), S2 (210g: 90g), S3 (180g: 120g), S4 (150g: 150g), S5 (120g: 180g). Data were analyzed statistically by analysis of variance and if there was a significant effect, further testing was done with BNJ at the level of 5%. The results showed that kluwih substitution in the manufacture of mureel fish shredded had an average: water content of 8.33-10.62%, protein :16.83-22.00%, fiber : 6.79-6.99%, score crispness 2-6.12, taste score 2.6-6.6. Based on the results of the analysis of the variety of kluwih substitutes and mureel fish have a significant effect on water content, protein content and crisp organoleptic test, taste on mureel fish fillet, and no significant effect on fiber content. The best kluwih substitution in S3 treatment with 120 grams of substitute kluwih and 180 grams of mureel fish.

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