天山阿特奥依纳克河流域冰川沉积序列

The Glacial Sediments Sequences in the Ateaoyinake River Valley, Tianshan Mountains

阿特奥依纳克河位于我国天山的最西段,最大现代冰川作用中心托木尔峰的南麓。在第四纪冰期与间冰期的气候旋回中,该处留下了形态较为完整的6套冰川沉积。应用ESR测年技术(辅以OSL测年技术)对冰碛物及其相应的冰水沉积物进行了定年,测得6套冰碛年龄分别为7.3±0.8kaBP(OSL,冰水沙);12.3±1.2kaBP(OSL)与15￣29kaBP;46￣54kaBP;56￣65kaBP;155.8±15.6kaBP与234.8±23.5kaBP;453.0±45.3kaBP,测年结果表明它们分别形成于新冰期、海洋同位素阶段(MIS)2、3b、4、6、12。第三套冰碛测年结果表明该处MIS3b冰进规模较大,其规模基本上与末次盛冰期(MIS2)的规模相当。此处最老冰碛测年结果与我国中段天山乌鲁木齐河源高望峰冰碛的测年结果(459.7±46kaBP与477.1kaBP)遥相呼应,老冰碛的年龄显示我国天山西段与中段至少于MIS12进入了冰冻圈,开始发育冰川。

Ateaoyinake River, located on the southern slope of the Tumer Peak in the western Tianshan Mountains in China, is the largest modem glaciation center. Six relative integrated sets of glacial tills formed in Quaternary glacial-interglacial cycles were reserved in this area. ESR dating technique （OSL dating technique as a supplementary method） was applied to determine the ages of the glacial tills and outwashes. The dating results of the six glacial groups are 7.3 ＋0.8 ka BP （OSL, outwash sand）, 12.3±1.2 ka BP （OSL） and 15-29 ka BP, 46-54 ka BP, 56-65 ka BP, 155.8±15.6 ka BP and 234.8±23.5 ka BP, 453.0±45.3 ka BP respectively, indicating that they deposited in Neoglaciation, MIS2, 3b, 4, 6 and 12. The results of the third set of the glacial tills demonstrate that a larger glacier advance happened in MIS3b in this area, similar with the extent of the Last Glacial Maximum （MIS2）. The age of the oldest glacial tills consistent with the ESR ages （459.7±46 ka BP and 477.1 ka BP） of the Gaowangfeng glacial tills at the headwaters of the Urumqi River, demonstrating that the western and the middle sections of Tianshan Mountains entered cryosphere at least in MIS12, resulting in development of the glaciers in that period.