地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
111 巻 , 4 号
選択された号の論文の18件中1~18を表示しています
  • 岩田 修二, 平川 一臣, 松岡 憲知
    2002 年 111 巻 4 号 p. 473-475
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 白岩 孝行, 山口 悟
    2002 年 111 巻 4 号 p. 476-485
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
    More than 400 glaciers exist in the mountains of Kamchatka Peninsula and they constitute the southern boundary of present-day glacierization along the eastern coast of the Eurasian continent. The mass balances of the glaciers are characterized by decadal and interdecadal oscillations, and they are closely related to those observed in the glaciers of Pacific North America. A negative relation was also found for the net accumulation timeseries reconstructed by ice cores from Ushkovsky Volcano, Kamchatka, and Mt. Logan, Canada, for the last 170 years. Because the oscillations of the net accumulation rate and the average annual δ 18O reconstructed from Ushkovsky-ice-core seem to be closely correlated with the so-called Pacific Decadal Oscillation (PDO) Index, it was suggested that the mass balances of the glaciers at both sides of the North Pacific had been affected not only by global warming trends but also by the interdecadal climate variability that had dominantly been occurring over the North Pacific.
  • 奈良間 千之
    2002 年 111 巻 4 号 p. 486-497
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
    Observational records of the locations of glacier termini, glacier mass balance, temperature, and precipitation, and field observations indicate recent glacier variations in the Pamir-Alai, central Asia. Glacier advances occurred at the beginning of the 1900s, and from 1960 to 1975. Small glaciers responded quickly after negative temperature anomalies. Glaciers in the Pamir-Alai and West Tien Shan advanced or stagnated, and those in the North Tien Shan retreated from 1960 to 1975. Then, these glaciers retreated markedly after 1975. The mass balance records of eight glaciers in the Pamir-Alai, North Tien Shan, and East Tien Shan since the 1950s show the same tendency. They were stable from 1960 to 1975, and decreased largely from the late 1970s. The variations of glacier termini from 1960 to 1990 in the Pamir-Alai and West Tien Shan coincide with the mass balance records, while the variations of glacier termini in the North Tien Shan do not coincide with the mass balance records. The differences in glacier variations since the 1960s between the Pamir-Alai and West Tien Shan, and North Tien Shan are due to differences in precipitation pattern.
  • 青木 賢人
    2002 年 111 巻 4 号 p. 498-508
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
    Glaciations during the Last Glacial in the Japanese Alps can be classified “azonal glaciation” and “zonal glaciation”. The ELAg (geomorphological equilibrium line altitude) of each former type of glacier is determined by Hs (height of summit), and is depressed by microclimatological phenomena such as drifted snow. The vertical/horizontal distribution of this type of glacier is azonal and sporadic. On the other hand, the ELAg of the latter type of glacier remains constant with Hs, and reflects the regional air temperature. In the case, the mountain ridge is higher than the regional equilibrium-line altitude, the vertical/horizontal distribution of glaciers belonging to this type becomes zonal and continuous. Modern examples of these two types of glaciation can be found in Kamchatka Peninsula, the Altai Mountains, and the Caucasus Mountains. These facts suggest that this classification is applicable to spatial and temporal variations of glaciation. Most of the Last Glacial glaciers in the Japanese Alps are classified into the “azonal glaciation” type. The glaciers belonging to the “zonal glaciation” type are located in the Northern Japanese Alps that have high altitudes. Some of the “zonal glaciation type” that existed during the Last Glacial Maximum stage were changed to “azonal glaciation” type during the Late Glacial stage. From this point of view, the Last Glacial glaciers in the Japanese Alps existed as a spatio-temporal transition between these two types. Paying attention to the “azonal glaciation” which is controlled by local conditions, is important for reconstructing the palaeoclimate based on the glacial landforms and their ELAs.
  • 山縣 耕太郎, 曽根 敏雄, 澤柿 教伸, Yaroslav D. MURAVYEV
    2002 年 111 巻 4 号 p. 509-518
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
    The Bilchenok Glacier in the central part of the Kamchatka Peninsula is located on the Ushkovsky Volcano (3900 m a.s.1.) and is regarded as a surging glacier. A tephrochronological study reveals Holocene fluctuations of the Bilchenok Glacier. Field survey and satellite and aerial photo interpretation indicate that five groups (moraines a to e) of moraines are present around the Bilchenok Glacier. Stratigraphic relationships among glacial deposits and marker tephras define the age of each moraine. Three glacial advances during the Neoglacial period are estimated to have occurred at 8 ka BP, 3 ka BP, and 1 ka BP. The glacier possibly expanded at 2 ka BP. No glacial landforms in the Little Ice Age were identified. Glacier expansion during the Little Ice Age was, therefore, on a smaller scale than that of glacial surges in the 1960s, and the other Holocene advances.
  • 岩崎 正吾, 澤柿 教伸, 平川 一臣
    2002 年 111 巻 4 号 p. 519-530
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
    In recent years, the “subglacial deforming bed” has attracted attention as a factor of glacier dynamics. Subglacial deforming beds, named T8-till and T9-till respectively in this study, were formed at two locations in the Hidak Mountain Range during the glacier's maximum advance (Poroshiri Stade) of the Last Glacial Stage. These subglacial deforming beds are characterized by deformation structures such as shear planes, folds and fault gouge formed under compaction in the vertical direction and drag in the horizontal direction. T8-till and T9-till had been deformed by two cycles and one cycle of glacial advance and retreat, respectively. Strain at these subglacial deforming beds reconstructed using shear angle and degree of fracturing indicate that T8-till developed beneath the first warm-based and the second coldbased glaciers, while T9-till was beneath the cold-based glacier.
  • 松岡 憲知
    2002 年 111 巻 4 号 p. 531-545
    発行日: 2002/08/25
    公開日: 2010/02/25
    ジャーナル フリー
    Asian high mountains involve a large area and a wide variety of periglacial environments. This paper reviews distribution, landscapes and geomorphic processes of mountain permafrost and periglacial belts in the Asian mountains. The lower limit of mountain permafrost descends northwards at a rate of about 160 m per degree of latitude. At the same latitudes, arid continental mountains have a lower limit about 1, 000 m higher than humid mountains, which contrasts with the subpolar mountain permafrost in Scandinavia. The altitudinal extent of the mountain permafrost belt commonly exceeds 700 m in the arid continental mountains, while it is generally less than 700 m in the humid continental and Pacific mountains. A non-permafrost but deep seasonal frost area usually lies between the lower limit of permafrost and the timberline. In the arid continental mountains, despite a vast extent of the periglacial environments, the lack of moisture minimizes frost action that produces typical periglacial landforms. However, the large height of the permafrost belt, when combined with local moisture sources, can produce very long rock glaciers and block streams. In the humid Himalaya, steep rockwalls impede the development of stony patterned ground and lobes in the upper part of the periglacial belt, while they favour debris production that feeds debris-covered glaciers. Low summit levels and creeping pine shrubs combine to narrow the periglacial belt in the Pacific high mountains. However, high freeze-thaw frequency aided by high moisture availability in these mountains leads to shallow but rapid frost weathering, heave and creep, resulting in extensive small-scale stony periglacial features. A systematic understanding of the periglacial environments in the Asian mountains requires field monitoring of the rates and mechanisms of periglacial processes with standardized modern technology.
  • 曽根 敏雄
    2002 年 111 巻 4 号 p. 546-554
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
    Palsas and peat plateaus in different stages of development, occur in the bog on the south of Mt. Hiragatake, the Daisetsu Mountains, Japan (43° 37' N). The internal structure of a palsa was investigated by drilling. The palsa consisted of a peat cover about 1 m thick and permafrost core of sand and silt. The permafrost base was at a depth of 523 cm. The analysis of the drilling cores revealed that a frost-susceptible silt layer, which contains many layers of ice-lenses, lies about 3 m deep below the ground surface. The silt layer was rich in ice and had volumetric and weight ice contents of 70-90% and 100-400%, respectively. Because the palsas in the bog cannot begin to heave until the frost penetrates to the silt layer at a depth of 3 m, they do not readily to grow in their early developmental stage.
  • 澤田 結基, 石川 守
    2002 年 111 巻 4 号 p. 555-563
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
    We found permafrost at the lower end of a block slope on Mt. Nishi-Nupukaushinupuri, Hokkaido Island. The distribution of the bottom temperature of snow cover (BTS), warm funnels at the top of the slope, and ground temperature changes on the block slope indicate continuous air circulation during the winter. In the spring, snowmelt water flows to the valley bottom, and refreezes on the perennial ice that fills the voids between coarse blocks. Simultaneously, ground temperatures abruptly increase at all depths in the active layer. These results strongly suggest that air circulation in winter, as well as the ice formation processes in spring control the thermal regime of the active layer of the block slope with a mean annual air temperature (MAAT) above 0°C.
  • 福井 幸太郎
    2002 年 111 巻 4 号 p. 564-573
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
    A pit survey, near-surface ground-temperature monitoring, DC resistivity tomography, and an eighteen-year interval survey elucidate the internal structure and the recent movements of the active protalus rampart in the Kuranosuke Cirque, the northern Japanese Alps. Permafrost was found beneath the lower part of the protalus rampart by using ground temperature monitoring and DC resistivity tomography. The results of DC resistivity tomography suggest that the materials of the protalus rampart has a at least 15 m in thickness. Four targets placed on the lower part of the protalus rampart moved at mean horizontally rates of 2.4 to 7 mm a-1 between 1983 and 2001. These displacements probably occurred due to permafrost creep and/or deformation in the lower part of the active layer.
  • 石川 守, 岩崎 正吾, 澤柿 教伸, 平川 一臣, 渡辺 悌二
    2002 年 111 巻 4 号 p. 574-582
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
    Year-round air and ground-surface temperature-monitoring indicated occurrences of mountain permafrost in the Hidaka Mountains, southern Hokkaido. The results of air temperature monitoring indicated that the temperature condition in the summit areas of the Hidaka Mountains is similar to that of the lower marginal limit of the discontinuous permafrost zone. Monitoring of the ground-surface temperatures shows that ground thermal regimes vary spatially with snow cover duration and thicknesses, and surficial materials. The permafrost underlies coarse blocky materials covered with thick seasonal snow cover within the Pleistocene cirques. These conditions suggest that mountain permafrost in the Hidaka Mountains is categorized as Mountain Side Permafrost (MSP), which is found beneath mountain slopes covered with thick seasonal snow cover where the mean annual air temperature is lower 0°C. The major controls on permafrost development and preservation are ground cooling before the onset of snow accumulations and cold air concentration through blocky materials. The presence of funnels emitting warm air throughout winter indicates that the cold air circulation plays an important role in the development and the preservation of MSP.
  • 青山 雅史
    2002 年 111 巻 4 号 p. 583-593
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
    Mean annual air temperature (MAAT), mean annual surface temperature (MAST), bottom temperature of winter snow cover (BTS), and morphometric parameters of rock glaciers indicate the states of the rock glacier activities in the Yari-Hotaka mountain range, Northern Japanese Alps. The air temperature conditions at the Mountain Hut Minamidake suggest that this monitoring site belongs to the discontinuous permafrost zone. The BTS and MAST values at the North and South Okiretto rock glaciers indicate the occurrence of permafrost. BTS and MAST at the Tenguppara I rock glacier indicate the absence of permafrost. At the North Minamisawa rock glacier, MAST was slightly above 0 °C, accordingly degrading permafrost that possibly exists in this rock glacier. These rock glaciers are not moving at present, as inferred from the morphologic and vegetational characteristics of these rock glaciers. These results suggest that the North Minamisawa, North Okiretto, and South Okiretto rock glaciers are of the inactive type, and Tenguppara I rock glacier is of the fossil type. The other rock glaciers in this mountain range are of the fossil type, as inferred from collapse and subdued forms, and extensive vegetation cover.
  • 苅谷 愛彦, 小松 陽介, 青山 雅史
    2002 年 111 巻 4 号 p. 594-600
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
    Weathering rind thickness of stones was measured on a crescentic ridge and on its surrounding low ridges and slopes in Yabusawa cirque (35° 43' N, 138° 11' E, 2, 885 m a.s.l.; est. MAAT-2.3°C) in the Akaishi Mountains, central Japan. Although a numerical time scale has not been established, the crescentic ridge, which is most likely of rock glacier origin, is considered to be the oldest at the study site from weathering rind data. Meanwhile, the debrismantled valley floor is estimated to be younger in the late Holocene. This fact suggests that more recent movement of rock glacier is proposed for the occurrence on landforms of the debrismantled valley floor.
  • 佐藤 正, 高柳 洋吉, 福井 幸太郎
    2002 年 111 巻 4 号 p. 601-604
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 岩田 修二
    2002 年 111 巻 4 号 p. Plate1-Plate2
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 岩崎 正吾, 澤柿 教伸, 平川 一臣
    2002 年 111 巻 4 号 p. Plate3-Plate4
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 松岡 憲知
    2002 年 111 巻 4 号 p. Plate5
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 澤田 結基, 石川 守
    2002 年 111 巻 4 号 p. Plate6
    発行日: 2002/08/25
    公開日: 2009/11/12
    ジャーナル フリー
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