干旱区地理2011，Vol.34Issue(5)：739-746,8.
天山乌鲁木齐河源1号冰川冰芯记录形成过程及年代划分
Chronology and record formation process of an ice core from Glacier No.1 at the Urumqi Riverhead in eastern Tianshan, China
摘要
Abstract
Glaciers ice core records the environmental information of the history. A suite of ice cores (T0 - T3) were recovered from 1991 to 1998 at Glacier No. 1 at the Urumqi Riverhead in eastern Tianshan, China, which are in the arid and semi - arid region in Central Asia, to explore the environmental information in the historical period in this area. As basic knowledge for the ice core dating,annual net accumulation (28.4 cm ieq) was determined by I-dentifying overlaps in chemical profiles of two ice cores drilled in different year, which is higher than on site mass balance budget, suggesting a potion of ice mass came from higher reaches of the glacier through ice flow. The study of formation process of light stable isotopic ratio and dust layer in the ice core during the past several years made a great contribution to the ice core dating. Annual net accumulation at drilling site is a very useful reference parame-. Ter in ice core dating. The annual net accumulation of surface snow at drilling site can be obtained from specific mass balance measurement at this site or through ice formation process observation. In order to resolve the uncertainties in the ice core dating and better interpret the records, a research program was conducted during the past several years under PGPI, which specifically focused on the effects of meltwater involved post - depositional processes on chemical species in snow - firn pack and the formation process of ice core records. This study has resulted in a number of outcomes with respect to the formation processes of various records in ice core and the effects of post depositional process on the snow - firn chemistry, etc. , which, particularly the results of evolution processes of dust layer and δl8O,has been proven to be very useful for the ice core dating and the records interpretation. Retrieved in October 1991, the 91.64 m T0 was the only core reached to bedrock. Both T1 and T2 were recovered in May 1996. With the lengths of 6.09 m and 80.1 m respectively. T3 was 14.08 m long and extracted in October 1998. All of the ice cores retrieved from a relatively flat site in percolation zone of Glacier No. 1 with elevations of 4 050 m for T0,T, and T2,4 040 m for T3. This paper presents chronology establishment process of T2(80.1 m). Cross counting of seasonal variations in chemical species profiles was employed for dating the top 32 m section. By comparing δ18O and Mg2 + profiles to temperature record reconstructed from tree rings, obtained were dating results in lower part of the core (33 -77.25 m) , which presents the age - depth relationship for the entire core, meanwhile, vertical formation velocity of visible dust horizons at drilling site leads to another age - depth equation. The result indicates that T2 contained 658 years. In addition, the ages of LJA moraines are coincident with cold or wet eras in the ice core records. And the study on the formation process of the ice core records provides with a theoretic base for the ice core dating.关键词
乌鲁木齐河源1号冰川/冰芯/定年/形成过程Key words
Glacier No.1/ice core/the chronology/formation process分类
天文与地球科学引用本文复制引用
王立伟,李忠勤,董志文,王飞腾..天山乌鲁木齐河源1号冰川冰芯记录形成过程及年代划分[J].干旱区地理,2011,34(5):739-746,8.基金项目
中国科学院知识创新工程重要方向项目(KZCX2-EW-311) （KZCX2-EW-311）
国家自然科学基金项目(91025012-y111141001) （91025012-y111141001）
中国科学院寒区旱区环境与工程研究所冰冻圈科学国家重要实验室基金项目(SKLCS-ZZ-2010-04)资助 （SKLCS-ZZ-2010-04）
