Last glacial climate instability documented by coarse-grained sediments within the loess sequence, at Fanjiaping, Lanzhou, China
Last glacial climate instability documented by coarse-grained sediments within the loess sequence, at Fanjiaping, Lanzhou, China
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中国兰州范家坪黄土序列中粗粒沉积物记录的末次冰期气候不稳定
DOI：
10.1016/j.yqres.2009.04.005
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发表时间：
2009-07-01
影响因子：
2.3
通讯作者：
Lu, Yanchou
中科院分区：
文献类型：
--
作者：
Jiang, Hanchao;Wang, Ping;Lu, Yanchou
对中国西部黄土高原范家坪黄土剖面进行了光致发光测年、粒度分析和磁化率测量。结果证实，最后一次冰期高频气候变化记录在中纬度大陆档案中。粒度记录表明，具有水平层理和河道充填结构的粗粒沉积物仅在几个较短的时间间隔内沉积，相当于海洋氧同位素阶段(MIS4)的开始和MIS3的早至中期。这可能意味着亚洲夏季风短暂的降雨增强，MIS3至MIS2晚期以来的消失可能是对北半球显著冰川冷却的响应。以往的研究表明，在MIS4开始时，高纬度的海面温度很高，而MIS3的早到中期加强了北半球夏季的日照，这意味着气候明显改善。气候改善有利于北方森林的恢复，提高了冬季和夏季的气温。由此产生的较小的赤道-极地温度梯度可能有助于饱含水分的夏季风向北渗透。因此，这项研究提供了关于陆地黄土性古环境对上一次冰期期间千年时间尺度气候波动的响应的新的重要信息。(C)2009年华盛顿大学。爱思唯尔公司出版，版权所有。
Optically Stimulated Luminescence dating, grain-size analysis and magnetic susceptibility measurements were conducted oil the Fanjiaping loess section, from the western Chinese Loess Plateau. The results confirm that last glacial high-frequency climatic shifts were documented in mid-latitude continental archives. The grain-size record indicated that coarse-grained sediments with horizontal bedding and channel-fill structures were only deposited in several short intervals, equivalent to the beginning of marine oxygen isotope stage (MIS) 4 and the early to middle MIS 3. This probably implies brief rainfall intensification of the Asian summer monsoon, and its disappearance since the late MIS 3 to MIS 2 may have been a response to significant glacial cooling in the Northern Hemisphere. Previous investigations revealed high sea-surface temperatures at high latitudes at the start of MIS 4, and the early to middle MIS 3 intensification of summer insolation in the Northern Hemisphere, implying evident climate amelioration. Climate improvement favors boreal forest recovery, enhancing both winter and summer air temperatures. The resultant smaller equator-polar temperature gradient probably helped the moisture-laden summer monsoon to penetrate northward. This study thus provides new significant information about the response of terrestrial loessic palaeoenvironments to millennial-timescale climatic fluctuations during the last glacial period. (C) 2009 University of Washington. Published by Elsevier Inc. All rights reserved.