中文摘要：

冻融作用是冰缘环境的一个重要地貌过程,其活动性直接反映气候变化,成为冰冻圈过程研究的重要内容.依据天山乌鲁木齐河源1991-2011年石环长期定位观测资料,对天山大陆性冰缘环境中石环发育特点和冻融作用机制进行深入探讨.结果表明:乌鲁木齐河源区石环冻胀作用在地表20cm内最强,直径为3cm的定位桩受到的冻胀作用最小,石环从中心向边缘冻胀作用变弱;对比石环发育和无石环的地表,前者冻融作用更强;海拔对冻胀作用有明显影响,在布设观测点的海拔3 500～4 000m范围内,随海拔上升,冻胀作用增强,到海拔3 900m达到最大,显示与当地现代冰川平衡线高度的吻合性.相关性分析表明,气候因素中夏季水热条件对石环发育作用较大,其中夏季降水对冻胀作用的影响显著,一年中地温在0℃波动的天数也是重要的影响因素;石环活动层定位观测揭示出冰缘地貌对区域气候变化反应敏感,对近20a温度升高有积极响应.

英文摘要：

Freezing and thawing is an important geomorphic process of the periglacial environment.Its activity is a direct reflection of climate change and thus it is an important part of the Cryosphere process.Based on a long-term monitoring in the source region of the ürümqi River from 1991 to 2011,a discussion in detail on the characteristics of sorted circles and frost heaving mechanism in the Tianshan Mountains is made in this article.In the source region,the effect of frost heaving is strongest within the surface layer of 20 cm deep,while the stake of 3 cm in diameter is least affected by frost heaving.Inside a sorted circle the frost heaving becomes weaker along radius from the center to the edge.Frost heaving in sorted circle area is stronger than that in the area without sorted circle.The altitude has significant effect on frost heaving.At the altitude range from 3 500 to 4 000 m,frost heaving enhances with altitude and reaches a maximum at 3 900 m,the equilibrium line altitude of glaciers.Correlation analysis demonstrates that the development of frost heaving and sorted circles has closely relation with moisture and thermal regime in the warm half year(from May to October).Frost heaving has positive relation with precipitation in the warm season,the transfer days when ground temperature undulates around 0 ℃ is also an important factor.The sorted circle monitoring reveals that periglacial landform is sensitive to regional climate change and has an active respond to the air temperature rising in recent two decades.