25 November 1991, Volume 13 Issue 4
    

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  • C. Lorius
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 283-289. https://doi.org/10.7522/j.issn.1000-0240.1991.0041
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    Ice cores from Greenland and Antarctica provide multiple proxy records of climate and environmental parameters. They show evidences of anthropogenic impact on atmospheric greenhouse gases. Increase over the last 200 years is 20% for CO2, 8% for N2O and more than 200% for CH4. They indicate glacial-interglacial surface temperature changes of -10℃, with cold stages associated with lower snow accumulation and high concentrations of marine and continental aerosols. The antarctic Vostok ice core has shown signatures of the insolation orbital forcing as well as a close association between temperature and greenhouse gas concentrations; CO2 and CH4 concentrations respectively increase bv about 40% and 100% during glacial-interglacial transitions. Greenhouse gas concentrations have likely played a significant part in the glacial-interglacial climate changes by amplifying, together with the growth and decay of the Northern Hemisphere ice sheets, the orbital forcing. Climate Sensitivity to greenhouse forcing estimated from paleo-ice core data is consistent with GCM simulations giving a 3-4℃ warming for a future doubled atmospheric CO2.
  • А.П.Мелъникова, Е.К.Баков
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 291-298. https://doi.org/10.7522/j.issn.1000-0240.1991.0043
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    The Holocene deglaciations are studied in some glacial valleys of Qon Kizilsu drainge basin, northern slope of Terskey Alatoo. Based on the buried paleosols and 14C dating, we conclude that the terminal positions of glaciers in 6000 a. ago were not lower than that of existing glaciers, and glaciers had retreated out valley bottom with elevation of 3100 m on the front zone of Terskey Alatoo mountain in the end of early Holocene (14C dating: 8610?190 aB.P.).The results of spore-pollen and 14C dating of Sharkratma (3560 m a.s.l.) and Shataly (3450 m a.s.l.) lake-marsh deposits situation in front of existing glacier show that between 5000-3000 a B.P. the climatic conditions were dry and warm, and quitly unfavourable for glacier existed.The new results above mentioned show that in Terskey range between 9000-3000 a B.P.full deglaciation probably took place and the glaciers had melted. And the existing glaciers are new formation in Neoglaciation. The glacier size before the Little Ice Age is smaller than that of existing glacier there. It could rule out the deglaciational model with stage and rhythm since last glaciation, and show characteristics of independent and young of existing glaciers.
  • Li Shuanke, Li Shijie
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 299-306. https://doi.org/10.7522/j.issn.1000-0240.1991.0044
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    Recently it has been discovered that many lakes on the north margin of Qinhai-Xizang Plateau had expanded during Last Glaciation Maximum, around 18 000 a B.P., and the lake level was 10-40 m higher than that at present. The lake transgression started and evded earlier in the west part than that in the east part of the plateau. The reasons of lake transgression during Last Glaciation Maximum are related to the increase of ice and snow melt-water in warm season and to the reduction of lake evaporation. The discovery of lake transgressional stratigraphy has important theoretioal significance for recorgnizing and evaluating the role of Qinhai-Xizang Plateau in Global environmental changes.
  • Wang Shilan, Chen Fahu, Cao Jixiu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 307-314. https://doi.org/10.7522/j.issn.1000-0240.1991.0045
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    The pollen analysis at a profile on the first terrace of south bank of Yellow River in Lanzhou for the first time reveals the characteristics of Sporopollen assemblage of this region since 10000 a B.P. The herbaceous and shrubbery pollens such as Chenopodiaceae, Artemisia sp., Ephedra sp., Gramineae, Reaumuria, which indicate arid and semiarid environment are the main elements in the profile. Although the Vegetation type has been grass since about l0000a B.P.. The pollen spectrum of the profile can be divided into three pollen zones according to the relationship among the pollen elements.The above characteristics of sporo pollen Assemblage show that the climate in Lanzhou basin have undergone the following changes during Holocene: temperate-dry, warm-moisture, warm-dry temperace-moisture, temperare-dry and cool-moisture.
  • Yuan Yujiang, Han Shuti
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 315-322. https://doi.org/10.7522/j.issn.1000-0240.1991.0046
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    In this paper, the series of annual precipitation of 526 years in the Northern of Xinjiang is reconstructed from tree rings, and reliability of the reconstructed precipitation series is verified by the istorical precipitation records, historical runoff records, and data of advancing and retreating of glacier. Then, periodicity of reconstructed precipitation series, trends of changing dry, about changing phenomenon and amplitudes of dry and wet are analysed. We find that little Ice Age begins at 1544 in the Northern of Xinjiang, calculate the anomalous percentages to mean precipitition of 526 years within the periods of advancing and retreating of glacier in little Ice Age, and the correlative features between precipitation and temperature in glacier advancing periods.
  • Li Shuxun, Cheng Guodong, Zhang Hongding, Chen Ruijie, Liu Jimin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 323-329. https://doi.org/10.7522/j.issn.1000-0240.1991.0047
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    It is shown by experimence that when specimen with varios size and shape cut from building brick was frozen in water and then was thawn one-dimentionally downword, water flowed through brick to the interface between ice and brick and frozen there, causing heave and sample moved up. Analoguous process might occur during the thawing of permafrost in the summer and accamulating rate of ice is accelerated near permafrost table.
  • Kang Jiancheng, He Yuanqing
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 331-336. https://doi.org/10.7522/j.issn.1000-0240.1991.0048
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    It was found through the field observation at four valley glaciers, longer than 20 km in the upper Shaksgam valley, the Karakoram, that there are regelation layers, subglacial cavities at ice-rock boundary, and some englacial and subglacial shearing belts.The grain size data of the subglacial debris show that the kurtosis on the grain size frequency curves is single type. With the increasing heat and melting water at ice-rock boundary, the mean grain size, skewness values decrease, and the Matrix index and Abrasion index increase; the ratios of grain size content between two sides of 2φ can show the degrees of the crushing and abrasion.The thickness of regelation layers are 20-30 cm at the bottom of terminal of Urdok and Stagar Glaciers. Melting water at ice-rock interface implies that the heat got at ice-rock boundary is larger than that translated out by ice. The analysis of debris grain size shows the grain size peak values are located area >2φ at frequency curves. Underneath the terminal of Singye glacier, some ice sliding marks no melting water, but can be seen on the ice of the cavity top, suggesting the getting heat under the glacier and the heat translated out by ice be in an approximate equilibrium; the debris grain size has a peak value spot at frequency curves located at region < 2φ. This result is agree with research at larger Gongba Glacier, Mt. Gong Ga. Thus, the area of subglacial debris grain size peak values located at the frequency curves is related with subglacial thermal regime, the point of 2φ at frequency curves is, possibly, a critical point.
  • Deng Yangxin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 337-342,330. https://doi.org/10.7522/j.issn.1000-0240.1991.0049
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    This paper discribes the size, petrological-mineralogical, surfaee and part of physical characteristics of till in Tianshan Mountain in China and the Soviet Union on the basis of contracting the analytical results of the till-soil samples taken from Tuyuksu Glacier in the Soviet Union, with the rekereme of the doccuments about the till in Tianshan Mountain by both Chinese and Russian scientists.The characteristics include: (1) wide distribution and various types; (2) breccia-soil fillers (<32 mm) which are mainly composed of graval and sand with inferior size grading; (3) complex clastic composition (over 40 species); (4) debris inferiorly abraded; (5) low maturity of light minerals; (6) distinct striae on the surface of bouldev and quartz sand; with conchoidal fracture; (7) high natural unit weight and generally low natural water content.
  • Long Zuoyuan
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 343-348. https://doi.org/10.7522/j.issn.1000-0240.1991.0050
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    The principle of apparent resistivity logging is introduced in this paper. If the soil type is the same the apparent resistivity of frozen stratum is much higher than that of unfrozen stratum. Therefore, there exist jump points of the apparent resistivity both at the top and the bottom interfaces of frozen stratum. By using the turning point on jthe curve of the apparent resistivity logging obtained from the system of potential and electrode with the distance between electrodes of 0.5 m, we can identify the locations of both the top and bottom interfaces and thickness of permafrost. The effect and accuracy of using the apparent resistivity logging curve to identify permafrost and its influencing factors, such as soil properties, ice content and drilling diameter are discussed.
  • Zhang Jinsheng, Masami Fukuda
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 349-357. https://doi.org/10.7522/j.issn.1000-0240.1991.0051
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    Present authors conducted experimental studies to estimate the hydraulic conductivity of partially frozen soils by means of needle probe method. The transport of heat in partially frozen soils occurs by conduction and by the convective transport of sensible and latent heat arising from the flow of water in gaseous, liquid and solid states. Theory describing the coupled flow of heat and water is used to determine an apparent thermal conductivity. Calculations suggerst that, at temperature close to melting point of ice in a frozen soil, the transport of latent heat may exceed the contribution of heat flux by conduction. Under these conditions, the apparent thermal conductivity becomes much greater than the bulk thermal conductivity. The differences between measured and bulk thermal conductivity of partially frozen soils derive the hydraulic conductivity of frozen soils. Estimated values of the hydraulic conductivity are consistent with previously reported ones.
  • Zhang Yaonan
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 359-362,358. https://doi.org/10.7522/j.issn.1000-0240.1991.0052
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    A new technique of capacitor scanning for removing alternate current noise and reducing systematic error is used in this temperature logger datalogger. Cold junction compensation is completed by high accurate temperature sensor AD590. This logger is composed of low cost thermocouple, PC-1500(A) pocket computer and logging section. The measured temperature ranges -50——+50℃; accuracy is 0.3℃ and logging interval is one point every ten seconds. This logger also includes thermocouple correction and can be changed of expanded according to different request.
  • Li Peiji
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 363-373. https://doi.org/10.7522/j.issn.1000-0240.1991.0053
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    This paper reviews the significant advances, principal progress, and breakthrough from studies of the Ice Ages and Milankovitch theory in the past two decades.With the improvements in dating and in interpretation of geological data and with advantage in consideing monthly insolation as well as with the development of climate models, it seems to have laid to Milankovitch renaissance. Observations on deep-sea cores and polar ice core demostrate that late Pleistocene climate is dominated by three broad-band cycles centered near periods of 23 kyr, 41 kyr, and 100 kyr. The periods’ of climate cycles match orbital cycles of precession, obliquity, and eccentricity. Each orbit-climate pair is significantly correlated. This evidence shows that both in the frequency and in the time domains orbital influences are felt by climate system. It is concluded that changes in the earths orbital geometry are the fundamental caure of the succession of Quaternary ice ages. And at least near the obliquty and precession frequecies, a considerable fraction of the climate variance is driven in some way by insolation changes forced by changes in the earths orbit. Modeling experiments show that the link betweeen orbital variations and climate not only was tied to ice volume but also to atmosphere circulations, deep water formation, and greenhouse gases.Among the competing theories and hypotheses to explain the coming and going of the Quaternary ice ages only the astronomical theory has been supported so far by substantial physical evidences. Except for the daily and annual cycles, there is no other place in the climatic spectrum for which this exactitude is possible. Consequently, the astronomical theory is the only one that can be used to predict precisely the duration of natural quasiperiodic changes in climate. Assuming no human interference at the astronomical scale, orbital forcing predicts that the general cooling that began 6 kyr B.P. will continue with a first moderate cold peak around 5 kyr A.P., a major cooling about 23 kyr A.P., and full ice age conditions 60 kyr A.P..
  • JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1991, 13(4): 375-380,374. https://doi.org/10.7522/j.issn.1000-0240.1991.0054
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