雅鲁藏布江中游12 ka BP前后的黄土堆积及其气候意义

doi:10.7522/j.issn.1000-694X.2015.00172

摘要/Abstract

摘要：

在青藏高原南部雅鲁藏布江中游的河流阶地上堆积着1~3 m厚的风成黄土,颗粒较粗,发育有不同程度的垂直节理。经光释光测试年代,发现它们形成于12 ka BP前后,是沉积速率达到0.47~1.49 m·ka^-1的快速黄土堆积。河流两岸高山上岩体经风化产生的碎屑物质汇集在河流谷地,在新仙女木(Younger Dryas,YD)时期干冷的气候条件下,经强劲的地表风搬运至山前平坦的河流阶地上,形成黄土堆积。这些黄土沉积揭示出YD时期青藏高原南部气候干冷,风沙活动强。

关键词: 雅鲁藏布江, 新仙女木时期, 黄土堆积, 光释光测年

Abstract:

Loess deposit is regarded as an indicator of arid and semiarid depositional environment during Pleistocene. On the basis of the reconnaissance, the eolian loess deposits of 1-3 m thick in middle reaches of Yarlung Zangbo River, Southern Tibetan Plateau, are analyzed. The loess sections are located at fluvial terraces far away from the riverbed. We applied optically stimulated luminescence (OSL) technique to dating the samples from these profiles, and measuring grain size distribution and magnetic susceptibility. The result shows that these sediments were deposited at about 12ka ago, when the climate was cold and arid, corresponding with the Younger Dryas (YD) event in high-latitude region. A large quantity of clastic materials produced by weathering of the mountains surface was transported and deposited along basins and valleys of the Yarlung Zangbo River by wind, gravity, glacial and water flow dynamics. With cold and dry climate through the YD period, these loess deposits were wind entrained and deposited. Our investigation provides new evidences that the southern Tibetan Plateau was cold and dry, with windy environment during the YD period.

Key words: Yarlung Zangbo River, Younger Dryas, aeolian loess, OSL dating

中图分类号:

P531

吴海锋, 鹿化煜, 张瀚之, 弋双文, 杨文斌. 雅鲁藏布江中游12 ka BP前后的黄土堆积及其气候意义[J]. 中国沙漠, 2016, 36(3): 616-622.

Wu Haifeng, Lu Huayu, Zhang Hanzhi, Yi Shuangwen, Yang Wenbin. A Climate Event at about 12 ka BP Revealed by Loess Deposit in Middle Reaches of Yarlung Zangbo River, Southern Tibetan Plateau, China[J]. JOURNAL OF DESERT RESEARCH, 2016, 36(3): 616-622.

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