Kooperativer Bibliotheksverbund

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Format: 27 S.

Series Statement: Japanese Antarctic Research Expedition : Scientific reports : Series C, Earth sciences 7

Content: Glaciological studies of the upper 10m of the ice sheet in East Antarctica were made during the JARE South Pole Traverse 1968-1969. The glaciological studies consisted of studies of surface snow and subsurface snow by means of pits as well as analyses of snow cores. Conditions of surface snow such as accumulation, roughness, density and hardness are described in this paper. It is found that the conditions are distinctly different in four regions along the route from Syowa Station to the South Pole, and that they have a close connection with the slope inclination. Relationship between the snow conditions and the slope inclination is discussed in terms of the dependence of wind speed on the slope inclination. Thus, it is concluded that the conditions of surface snow are mainly controlled by wind speed. Measurements of annual snow accumulations disclose that local variations in accumulations take place in a strong wind region, and coincide with local topography of the region. Also, distinct regional differences in accumulations during the summer season are discussed from the differences between cyclonic and anticyclonic precipitations. Studies of subsurface snow in 2m deep pits indicate that regions located in the north and south of 73°S are characterized respectively by compact fine-grained snow and well-developed depth hoar. Analyses of snow cores from the surface to a depth of 10m revealed the distribution of snow density in the upper 10m of the ice sheet along the route from Syowa Station to the South Pole. Regional profiles of snow density at the depths of 5 and 9m were different from those at the surface. This is due to the differences in the mean annual air temperature.

Note: MAB0014.001: ZSP-594/C-7 , Online frei verfügbar

In: Japanese Antarctic Research Expedition

URL: https://nipr.repo.nii.ac.jp/?action=repository_opensearch&index_id=325

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Format: 13 S.

Series Statement: Japanese Antarctic Research Expedition : Scientific reports : Series C, Geochemistry 6

Content: The deuterium content of 40 samples of water substances from Antarctica was determined mass spectrometrically. Snow samples gave -13.4 to -21.2% for δDsMOW. From these and PICCIOTTO's data, -13.4 to -29.9%, as well as a value -32.0% for the 14 meter deep water of Lake Bonney, Victoria Land, the source of which is assumed to be in the snow in the surrounding area, the possible lower extreme of deuterium fractionation on the earth was given. The value of δDsMOW for continental ice ranged from -15.0 to -23.0%, being similar to those for snow; this fact shows that fallen snow was transformed into glacial ice through no perceptible isotopic fractionation. The value of δDsMOW for pack ice fluctuates around the sea water value, indicating that the major source of this kind of ice is sea water. The chlorine determination supports the view. Puddle water was found to be rather uniform in the content of salt, the major source of which was concluded to be sea water spray or air-borne salt. The results of the determination of δDSMOW, -4.3 to -10.9%, indicate that the source of water is partly land water and partly sea ice, but the direct supply of sea water, if any, must be insignificant. A number of ponds on the East Ongul Island is characterized by a rather high salinity and a ratio Na/Cl smaller than that for sea water. The value of δDsMOW was found to be intermediate between snow water and sea water. From these results it was concluded that the salt of the ponds was transported from the surrounding seas in the form of sea water spray and that the observed value of δDsMOW was caused by fractional concentration of deuterium through evaporation. Thus, the characteristics of different kinds of water substances from Antarctica were clarified and, at the same time, the history of their formation was elucidated.

Note: MAB0014.001: ZSP-594/C-6 , Online frei verfügbar

In: Japanese Antarctic Research Expedition

URL: https://nipr.repo.nii.ac.jp/?action=repository_opensearch&index_id=23

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Format: 42 S.

Series Statement: Japanese Antarctic Research Expedition : Scientific reports : Series C, Geology 4

Content: Results of soundings carried out during five Japanese Antarctic Research Expeditions are summarized. The bottom sediments collected by the 5th Expedition were analyzed concerning the grain size distribution, chemical composition, gravel composition, heavy mineral association, clay mineral composition and organic matters. The area studied is divisible into at least four sedimentary petrographic subprovinces on the basis of gravel composition, heavy mineral association and clay mineral composition. It is probable that these sediments were transported to the present sites from different sources without much sorting effects. The occurrence of trioctahedral illite in clay fraction may be the result of weak chemical weathering in the Antarctic region.

Note: MAB0014.001: ZSP-594/C-4 , Online frei verfügbar

In: Japanese Antarctic Research Expedition

URL: https://nipr.repo.nii.ac.jp/?action=repository_opensearch&index_id=20

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Format: 27 S.

Series Statement: Japanese Antarctic Research Expedition : Scientific reports : Series C, Geology 3

Content: The Yamato Sanmyaku is a mountain range located at about 200km south of the Prins Harald Kyst, East Antarctica. The range forms an arcuate chain, extending 50km north-south, comprising seven massifs temporarily named A, B, C, D, E, F and G. The rocks of the area are divided into a charnockitic group (pyroxene gneisses and pyroxene syenites) and a granitic group (migmatitic gneisses, granitic gneiss, and microcline granites). In addition, metabasite interlayers and metadikes are found everywhere, associated with microcline pegmatites. The charnockitic group is involved in the older complex which crystallized under the conditions of a granulite facies. It has been partly modified by later granitization related to the granitic group which itself shows various stages of granitization. The grade of metamorphism increases towards the north, parallel to the gneissosity. The intercalated metabasite layers correspond to the host rocks in mineral paragenesis. Basic dikes are intruded obliquely into both the granitic gneisses and the pyroxene syenites, and are metamorphosed into various metabasites under the conditions of an amphibolite facies. This metamorphism is probably related to the subsequent intrusion of microcline granites and associated microcline pegmatite. A thrust movement from east to west represents the last stage of the structural evolution.

Note: MAB0014.001: ZSP-594/C-3 , Online frei verfügbar

In: Japanese Antarctic Research Expedition

URL: https://nipr.repo.nii.ac.jp/?action=repository_opensearch&index_id=19

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Format: 12 S.

Series Statement: Japanese Antarctic Research Expedition : Scientific reports : Series C, Geology 1

Content: The chemical compositions of constituent minerals of metamorphic rocks of the area around Lutzow-Holm Bay in Antarctica are described along with their optic properties. The mineralogy and paragenesis of metamorphic rocks are interpreted as that the metamorphic rocks in this terrane belong to the granulite facies.

Note: MAB0014.001: ZSP-594/C-1 , Online frei verfügbar

In: Japanese Antarctic Research Expedition

URL: https://nipr.repo.nii.ac.jp/?action=repository_opensearch&index_id=17

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Format: 40 S.

Series Statement: Japanese Antarctic Research Expedition : Scientific reports : Series C, Geology 5

Content: The Yamato Sanmyaku is a mountain range located about 200km south of Prins Harald Kyst, East Antarctica. The mountains are composed of charnockitic group and granitic group rocks which were described geologically and petrographically by K. KIZAKI (1965). The present paper deals with the potash feldspars from the charnockitic group and pegmatites. The occurrence of the potash feldspars and their optical characteristics are described first, revealing the mechanism of albitization of potash feldspars which have a wide range in the optical axial angle. Next, the two-feldspar geothermometry method is applied to the potash feldspars from the Yamato Sanmyaku and the results are compared with that of the Norwegian potash feldspars and also with the data of Japanese plutonic rocks. The formation temperatures estimated from the distribution coefficient k, triclinicity and 2Vx value are discussed on the basis of the subsolidus phase relation, the relation between the formation temperature and crystal symmetry, and the relation between the optical axial angle and triclinicity. These relations well support the conclusion held from the geological and petrographical points of view that the charnockitic rocks were originally formed under a granulite facies condition, but their characters were influenced more or less by the subsequent granitization under an amphibolite facies condition.

Note: MAB0014.001: ZSP-594/C-5 , Online frei verfügbar

In: Japanese Antarctic Research Expedition

URL: https://nipr.repo.nii.ac.jp/?action=repository_opensearch&index_id=21

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Format: 24 S.

Series Statement: Japanese Antarctic Research Expedition : Scientific reports : Series C, Geology 2

Content: The East Ongul Island on the coast of the Lutzow-Holm Bukt, East Antarctica, was investigated from the tectonical and petrographical points of view. The rocks exposed in the island are petrographically classified into the following seven types : 1) Metabasites, 2) Pyroxene gneisses, 3) Hornblende gneisses, 4) Garnet gneisses, 5) Granites, 6) Feldspathic rocks, and 7) Pegmatites. It is verified that the unique structural feature of the island is represented by the isoclinal fold recumbent to the west with the frontal zone in which many small anticlinal as well as synclinal folds occur. The inner core of the main anticline is generally composed of the garnet gneisses with the pyroxene gneisses forming the outer mantle. The hornblende gneisses, which are distributed in front of the recumbent anticline, occur in the same horizon as the pyroxene gneiss, so the former may have been converted from the latter. This is also confirmed by the geological and petrographical observations. Besides, the hornblende gneiss zone coincides with the zone of granite and subsequent microcline pegmatite emplacement. The lineation of the rocks, represented by the undulating foliation, is defined to be a b-lineation parallel to the fold axis, but another lineation with the same character but perpendicular to the fold axis is also found. The fracture systems indicated by the pegmatite and joint patterns were analyzed by tectonic dating. The pegmatite intruded at the earlier folding stage, whereas the joint pattern was formed at the later upwarping stage. The gneisses and granites are classified mainly by the characteristic mafic minerals, and their modes of occurrence as well as the optical mineralogy are described. The optical data of the constituent minerals revealed that there is a tendency that the Fe/Mg ratio of the mafic minerals such as pyroxene, hornblende, biotite and garnet, may increase with acidity of the rocks, from the matabasites to the granites. The anorthite content of plagioclase is restricted within a rather narrow range between 22% and 35% when feldspar coexists with potash-feldspar, although that of plagioclase in metabasite and basic enderbitic pyroxene gneiss free from potash-feldspar ranges widely from 42% to 93%. The triclinicity of the potash-feldspar may become higher in the granite than the gneisses judging from the data of their 2V values. It is probable that the gneisses were formed originally under the condition of a granulite facies in the regional metamorphism. At the same time, the widespread developement of hornblende and biotite in the metabasites and gneisses suggests subsequent changes in temperature and pressure or the presence of water as well as changes in chemical composition which facilitated the mobilization and plastic deformation of the rocks. It is considered that two phases of metamorphism may be detected in the area; the granulite facies at an earlier phase and the amphibolite facies at a later phase. This has been suggested by the investigations not only in other regions of the East Antarctica but also in other Precambrian shields of the world.

Note: MAB0014.001: ZSP-594/C-2 , Online frei verfügbar

In: Japanese Antarctic Research Expedition

URL: https://nipr.repo.nii.ac.jp/?action=repository_opensearch&index_id=18