摘要
通过对昆仑山北麓阿羌黄土剖面AQS3层段的年代测试、粒度参数(Mz和σ)以及主要氧化物(SiO2,Al2O3,TOFE(Fe2O3+FeO)和(Al2O3+TOFE)/SiO2比值)分析,并结合区域相关地层反映的古环境和腹足类化石指示的古生态,认为AQS3记录了末次间冰阶19个旋回的干冷与暖湿的气候波动。其中,15个具有千年尺度旋回的各个温暖期能够较好地与GRIP冰芯氧同位素曲线中的D-O事件在时代和气候性质上进行一一对比。可能是由于地处毗邻冰川山麓、加之海拔较高,故该层段粒度与主要氧化物显示的气候变动的幅度并不大,然而却相当敏感。不仅于此,这种千年尺度的温暖气候变化在昆仑山北麓及其近邻区域也有明显的表现。例如,在昆仑山北麓普鲁地层剖面中,指示暖干气候作用下形成的含石膏等盐类的砂土砾石层的TL年龄为距今31000年、45500～41600年、45900年和54500年,可以依次与GRIPδ18O中的间冰段D/O6,D/O12,D/O13和D/O15进行对比;在阿尔金山北麓,类似的并具有荒漠漆的砂土砾石层的TL年龄为37200aB.P.和59700aB.P.,分别相当于D/O9和D/O17间冰段;在塔克拉玛干沙漠腹地的高阶地(海拔1310m),可能代表了剧烈升温的气候背景下,环塔里木盆地四周高山冰雪大量消融导致的塔克拉玛干沙漠腹地的"大湖期",其日历年为33197aB.P.,与GISP2冰芯氧同位素曲线在33000aB.P.的暖阶段相当。发生在昆仑山北麓及毗邻区域AQS3时期若干温暖阶段的地层学证据以及其在时间上能够与GRIP和GISP2冰芯氧同位素曲线相关暖峰的耦合,表明由阿羌剖面末次间冰阶粒度和主氧化物峰谷变化反映出来的多次冷暖波动,其根本原因还是受到北半球D/O振荡的强烈影响。
Based on the age determination,grain-size parameters Mz and σ, contents of SiO2 and Al2O3 ,TOFE（Fe2O3 ＋ FeO） and the ratio of（ Al2O3 ＋ TOFE）/SiO2 for the AQS3 segment of the Aqiang loess section in the north piedmont of the Kunlun Mountains, together with the paleoenvironment reconstructed by related strata and the paleoecology by fossil gastropods in this region,we conclude that the AQS3 segment recorded 19 cycles of cold-arid and warm-humid climatic fluctuations during the last interstadial. Each warm phase in the 15 millennial-scale cycles corresponds well with the D/O events in the δ^18O curve of GRIP in terms of ages and climatic features respectively. Maybe as being in the piedmont with glaciers nearby and in a high altitude, the climatic fluctuations indicated by grain-sizes and major oxides of this segment are small, but very sensitive. Moreover, similar warm climate fluctuations at the millennial scale are recorded clearly in the north piedmont of the Kunlun Mountains and its adjacent area. For example, the TL ages of sandy soil and gravel layers with such saline minerals as gypsum formed under the control of warm-arid climate in the Pulu stratigraphic section in the north piedmont of the Kunlun Mountains are 31000aB. P., 45500aB. P. to 41600aB. P., 45900aB. P. and 54500aB. P., corresponding to the interstadials D/O6, D/O12, D/O13, and D/O15 in the δ^18O curve of GRIP, respectively. Similarly, those with desert lacquer in the north piedmont of the Ahunshan Moutains are 37200aB. P. and 59700aB. P.,corresponding to the interstadials D/O9 and D/O17,respectively. The Megalake Period on the high terraces（ 1310m above sea level）in the hinterland of the Taklimakan Desert resulted from plenty of ice-snow melt runoff from the high mountains around the Tarim Basin on a climatic background of rapid warming has its calendar age of 33197aB. P.,corresponding to the warm phase of 33000aB. P. in the δ^18O curve of GRIP. The stratigraphic evidences on several warm phases of the AQS3 segment in the nor
出处
《第四纪研究》
CAS
CSCD
北大核心
2008年第1期140-149,共10页
Quaternary Sciences
基金
国家重点基础研究发展规划项目(批准号:2004CB720206)
中国科学院知识创新工程重要方向项目(批准号:KZCX2-SW-118)
香港政府研究基金项目(批准号:HKU7243/04H)
中国科学院地球环境研究所黄土与第四纪地质国家重点开放实验室基金项目(批准号:SKLLQG0008)资助
关键词
昆仑山北麓
阿羌黄土剖面
AQS3层段
末次间冰阶
千年尺度气候变化
north piedmont of the Kunlun Mountains, Aqiang loess section, AQS3 segment, last interstadial, millennial-scale climate fluctuation
