25 May 1995, Volume 17 Issue 2

    

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  Studies on Altitude and Climatic Environment in the Middle and East Parts of Tibetan Plateau during Quaternary Maximum Glaciation

  Shi Yafeng, Zheng Benxing, Li Shijie, Ye Baisheng

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 97-112. https://doi.org/10.7522/j.issn.1000-0240.1995.0013

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  A wide variety of informations is used in this paper to comprehensively infer the altitude and climatic environment during Quaternary maximum glaciation. It is suggested that the time of Quaternary maximum glaciation appearance is in correspondence with the deep sea core oxygen isotopic stages 18-16(0.72-0.52MaBP). At that time the height of the Plateau was approximately 1000 m lower than that at present, the total glacierized area of four major mountain ranges(Tanggula, A’nyemaqen, Golog and Daocheng Haizi)in the middle and east parts of the plateau was 40000km², 18 times larger than that at present, the eqilibrium line altitude varied from 3450 to 4250 m, the average air temperature from June to August varied from 2.3 to 3.4℃, and the annual precipitation varied between 1260 and 1960 mm, 1.8to 3.2 times more than that at present at the equilibrium line altitude.
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  Glaciers and Their Fluctuations in Mt. Mungun-Tayga

  Xie Zichu, Yu. P. Seliverstov, K. B. Chestyakov, E. G. Moskalenko

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 113-119. https://doi.org/10.7522/j.issn.1000-0240.1995.0014

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  Near the center of Asia, the Mungun-Tayga in Tuwa, Russia, is an independent glaciated region. There are 36 glaciers with an area of 27.8 km², which have a main supply from westerly and local circulations, and characteristics of subcontinental type of glaciers. The area of glaciers has been reduced by 49.3% since the Maximum of the Little Ice Age. For recent 150 years, the area and lengths have decreased, and the altitudes of terminal and snow line have increased. Over the recent 30 years, the retreating rate of glacier has increased, there is a fluctuation of glacier mass balance with a period of about 10 years. At the present, the glaciers are in negative balance. However, two glaciers advanced suddenly from 1992 to 1993. It is found that the glacier change is distinctive in this region in comparison with those in other mountains in central Asia, which means that the response of glacier to global change is complicated in different regions.
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  Permafrost Degeneration in the East of Tibetan Plateau

  Zhu Linan, Wu Ziwang, Liu Yongzhi

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 120-124. https://doi.org/10.7522/j.issn.1000-0240.1995.0015

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  The zoning boundaries of permafrost are theoretically determined from the relation between permafrost and modern climate in this paper. The boundary elevations are given in a profile. There are many phenomena demonstrating a commom degeneration such as buried frozen soil, pseudo-permafrost landforms variations of patchy permafrost table,multigelation, and vegetation changing in different regions. The important conclusion is that a basic trend of the permafrost changing in the plateau is degeneration.
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  Relations between Weather Systems Affecting Tibetan Plateau and Oxygen Isotope in Precipitation

  Zhang Xinping, Yao Tandong

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 125-131. https://doi.org/10.7522/j.issn.1000-0240.1995.0016

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  Weather systems have significant effect on δ¹⁸O in precipitation on Tibetan Plateau.Generally, under the influence of westerly trough, the change of δ¹⁸O in the Plateau is sychronous with that of temperature. Under the influence of shearing line and plateau low-eddy, the change features of δ¹⁸O in the monsoon regions of the Plateau are similar to that in coast stations or island stations in the low latitudes where there is marked negative correlated relation between δ¹⁸O and precipitation or temperature, while the variation characteristics of δ¹⁸O in the non-monsoon regions of the Plateau are alike with those in the continental stations in the mid-high latitudes where remarkable positive correlated relation between δ¹⁸O and temperature is found.
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  The Vegetation and Climatic Changes in Zoige During the Last 20000 years Determined by Pollen Records

  Liu Guangxiu, Shen Yongping, Wang Rui, Wang Suming

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 132-137. https://doi.org/10.7522/j.issn.1000-0240.1995.0017

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  The pollen records from Zoige, located in the northeastern Tibetan Plateau, indicate that the climate in this area was unstable during the last 20000 years. The relative warm periods took place about 20-18, 16-15, 13-12, 11-6, 5-3kaBP, the cold ones occured about 18-16, 15-14, 12-11 and 6-5kaBP. Last Glacial Maximum was about 18-16kaBP. The cold event of 12-11kaBP could correspond with Younger Dryas. From 11kaBP the forest vegetation was developing, which represented the coming of Holocene.During 9-3kaBP, the coniferous and deciduous broadleaf forest showed the Holocene Megathermal and reached the maximum about 7-6kaBP as Rhus and Castanea presented inthe forest. About 6-5kaBP absence of pollen might reflect a cole climate in Holocene.
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  Mass Balance on the Dongkemadi and Meikuang Glaciers in 1992/1993

  Pu Jianchen, Yao Tandong, Zhang Yinsheng, K.Seko, K.Fujita

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 138-143. https://doi.org/10.7522/j.issn.1000-0240.1995.0018

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  Based on the observation in 1992/1993, mass balance of Da Dongkemadi glacier and Xiao Dongkemadi glacier in the Tanggula Mountains and Meikuang glacier in the Kunlun Mountuins were calculated. It was found that mass balances of these glaciers were all positive, 289.7mm, 211.4mm and 95.7mm respectively, with an obvious regional difference in mass balance, i.e., mass balance of the glaciers in the Tanggula Mountains in the central part of Tibetan Plateau was larger than that in the Kunlun Mountains in the margin of the plateau. Owing to the effect of seasonal climatic variation on the mass exchange of these glaciers, the processe of mass balance in an year have four stages, two intensive accumulation periods in the begainning and the end of warm season, an intensive ablation period in the warm season, and a period lasting about 8 months(which span over the cold season)with fluctuations of mass balance in a low level. Different from glaciers in other mountains, mass balance of these glaciers undulatingly increases with height.
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  Some Tensile Creep Characteristics of Frozen Loess

  Shen Zhongyan, Miao Lina, Liu Yongzhi

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 144-151. https://doi.org/10.7522/j.issn.1000-0240.1995.0019

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  Some deformation characteristics of tensile creep revealed by a test of frozen saturated loess are presented in this paper. Similar to compressive creep, decay creep and undecay creep can be distinguished. As for undecay creep, there are also three phases, i.e. steady, unsteady and failure phases. As compared with compressive creep, less deformation of tensile creep occurs until cracking. The deformation in phase Ⅲ is a little one, lasting a short time. The ultimate fracture is brittle, regardless of temperature. A creep equstion is derived from the strain rate-time curve successively, which may well describe the strain at the phase Ⅲ.
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  Analysis of Microstructural Changes in Frozen Sandy Soil Under Confining Pressures Using Scaning Electronic Microscope

  Ma Wei, Wu Ziwang, Chang Xiaoxiao, Wang Jiacheng

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 152-158. https://doi.org/10.7522/j.issn.1000-0240.1995.0020

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  Using scaning electronic microscope we observed the microstructural changes of frozen saturated Lanzhou sandy soil under the conditions of-5℃ and high confining pressure(0-22MPa). Combining with the macrocharacteristics of effect of confining pressure on strength behaviour of frozen soil, it is found that 1)When 0≤σ₃ <8MPa, structural densification and strengthening are dominant, so that strength of frozen soil increases with increase of confining pressure, 2)When 8≤σ₃<16MPa, crushing appears in some particles and melting appears in the contact ice between particles, so that strength of frozen soil decreases slowly with increase of confining pressure, 3)When σ₃≥16MPa, the crushing of particles is intensified and larger cracks appear in some of granules and structure join is damaged, so that strength of frozen soil decreases suddenly with increase of confining pressure.
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  The Study of Practicability of Photoviscoelastic Simulation Test for Frozen soil’s Creep

  Wang Tingdong, Wu Jianjim, Zhao Xishu, Wu Ziwang, Liu Yongzhi

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 159-163. https://doi.org/10.7522/j.issn.1000-0240.1995.0021

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  The practicability of photoviscoelastic simulation test for frozen soil’s creep is studied in this paper such as determining parameters of frozen soil’s creep, making material of photoviscoelastic test and theoretical solution of plane problem. It is practical to apply the required conditions in simulation creep test of frozen soil.
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  Modeling Test on the Building with Short Piles and Ventilating Foundation in Permafrost Regions

  Zhu Linnan, Li Dongqing, Guo Xingming, Yu Chongyun

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 164-169. https://doi.org/10.7522/j.issn.1000-0240.1995.0022

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  The paper presents an integral similar modeling test of a building with permafrost base.The tested results are in good agreement with the real. By simulating the dynamic process of a building in laboratory, we give a further evidence that the allowable bearing capacity of frozen soil R_f is reliable, when the confined layer is the ice layer with soil, in the same time,we can assure that, when the mean annual ground temperature of frozen soil T_cp=-2.5℃, the mean ground temperature of the confined layer can be taken as T=-0.5℃, and the allowable bearing capacity R_f=0.1MPa, thus only single-storey house can be built, when T_cp=-4.0℃,T=-1.0-1.2℃, R_f=0.15-0.17MPa, under certain conditions, two storey house can be built.
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  The Response Functions of Tree-Ring Chronologies in Western Tianshan Mountains

  Yuan Yujiang, Li Jiangfeng

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 170-177. https://doi.org/10.7522/j.issn.1000-0240.1995.0023

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  In this paper, using the analytical technique of response function, we study the climatic information from tree-ring chronologies in Ili Prefecture. Some useful conclusions is obtained, which is helpful to understand the effect of climate on forest in the Prefecture and to extract the climatic information from the tree rings in warm and wet region.
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  The Features of Nivation Landforms in the Changbaishan Mts.

  Song Changqing, Cui Zhijiu, Liu Gengnian, Zhu Cheng

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 178-183. https://doi.org/10.7522/j.issn.1000-0240.1995.0024

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  There are plentiful nivation landforms distributed widely in the Changbaishan Mts., especially nivation hollows and cryoplanation terraces. Compared to other areas, the nivation landforms have the features of small scale, younger age and complicated causes. In addition,semi-location observation found that the low erosive velocity of nivation hollows have inhomogeneity.
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  Permafrost Distribution in the Dabanshan Pass Section of Ning-Zhang Highway in Eastern Qilian Mts.

  Wang Shaoling, Chen Xiaobai, Zhang Zhizhong

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 184-188. https://doi.org/10.7522/j.issn.1000-0240.1995.0025

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  The annual precipitation in Dabanshan region is the highest in Qinghai Province,amounting to 850mm. Snowfall frequently occurs in Dabanshan pass section of the highway during the cold period. The thickness of stable snow cover in the region is generally 70-80cm and the thickest can be 200-300cm. The period with stable snow cover can be aslong as 180-200 days. The dominant effect of snow cover insulation, accompaning by the influence of local climate, results in higher lower limit of permafrost(about 200m higher than that in nearby region), higher mean annual ground temperature. less permafrost thickness and rather unstable permafrost state in the region.
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  Rapid Calculation of Direct Radiation on Sloping Fields

  Wang Jian, Lu Anxin, Li Wenjun, Tang Han

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1995, 17(2): 189-192. https://doi.org/10.7522/j.issn.1000-0240.1995.0026

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  For calculating radiation on micro-terrain, it’s important to analyse the harshness of relief. Slope and aspect needed in the analysis can be obtained from DTM. Referred to the Method of Jeff Dozier and James Frew, this paper presents a procedure to calculate the slope,aspect and solar illumination angle and so on. At last, the results are compared to observations.