中文摘要：

本文应用全溶样品的等时线模式,较成功地测定了藏北高原西南部扎布耶盐湖SZK01孔岩芯中含不等量碳酸盐粘土的230Th/238U年龄,建立了青藏高原腹地海拔4000m以上湖泊120ka以来连续的同位素年龄标尺,从而为扎布耶盐湖及其周缘地区古环境古气候演化研究奠定了时间坐标。根据230Th/238U年龄数据,SZK01孔的平均沉积速率约为68cm/ka。然而不同层段的沉积速率差异较大,变化在20.8～128.8cm/ka,其快慢变化反映了该湖从短命深湖、动荡浅湖、滨湖到盐湖的环境变化,与高分辨率SZK02孔的研究结果相一致。讨论了测年模式的适应性、样品的U封闭性和应用的优越性,提出开展湖区及周边各类型水体的U、Th同位素化学行为研究和检验沉积物中多源Th对定年的影响将是今后年代学研究的重要内容。

英文摘要：

The authors used the U-series isochron model of total sample dissolution to determine successfully the age of clay sediments with varied contents of carbonate in the core taken from hole SZK01 in Zabuye Lake in the southwest of the northern Tibetan Plateau and established the continuous isotope timescale of lakes 4000 m above sea level in the last 120 ka in the interior of the Tibetan Plateau,thereby providing the time-space coordinates for the research on the paleoclimate and paleoenvironment in the Lake Zabuye region and its neighboring areas as well as the relationship between evolution of the Tibetan Plateau and global changes.According to the data of 230Th/U ages,the average sedimentation rate at hole SZK01 is about 68 cm/ka.However,the sedimentation rates of different intervals differ greatly,varying from 20.8 to 128.8 cm/ka.This variation reflects the implication of the environmental change of the lake from an ephemeral deep lake through an undulating lake and lakeshore to a salt lake,which is consistent with the result of the study of high-resolution hole SZK02.In this paper,we discuss the adaptability of the dating model and the U sealing of samples and superiority of its application.Further work on the U and Th isotope chemical behaviors in various hydrologic regimes and examination of the effects of multiple Th sources in sediments on dating is necessary to develop the U-series technique for the study of late Quaternary lacustrine deposits and paleoclimate of arid and semiarid continental environments.