末次冰期以来新疆伊犁黄土的稀土元素特征及环境演变  

RARE EARTH ELEMENT CHARACTERISTICS AND ENVIRONMENTAL CHANGES RECORDED BY LOESS DEPOSITION IN THE ILI BASIN SINCE THE LAST GLACIATION

作　　者：陈秀玲[1,2] 李金婵[2] 方红[2] 朱甜英 黄雨振 

机构地区：[1]福建师范大学地理研究所,福州350007 [2]福建师范大学地理科学学院,湿润亚热带山地生态国家重点实验室培育基地,福州350007

出　　处：《第四纪研究》2017年第1期14-24,共11页Quaternary Sciences

基　　金：国家自然科学基金项目（批准号：41302149、41572162和U1405231）、中国科学院国际合作局对外合作重点项目（批准号：132861KYS20160002）和中国科学院交叉创新团队项目（批准号：中国科学院人字〈2013〉47号）以及福建省公益类科研院所基本科研专项项目（批准号：2014R1034-2）共同资助.致谢 感谢中国科学院地球环境研究所宋友桂研究员在本文写作过程中给予的支持与帮助,以及其研究生在样品采集和整理方面提供的帮助;感谢杨美芳编辑对本文所提出的宝贵意见和提供的耐心帮助.

摘　　要：西风环流是北大西洋气候区和东亚季风气候区之间的联系纽带，研究西风环流是深入研究东亚季风和高低纬气候遥相关的重要补充和延续，也是全球气候变化机制研究的一项重要内容。新疆伊犁盆地常年深受西风环流影响，盆地内黄土是研究西风环流演变历史的良好素材。本文以伊犁盆地昭苏波马黄土-古土壤剖面（ZSP）为研究对象，对其开展系统的稀土元素地球化学研究。研究结果表明：ZSP剖面稀土元素总量（ΣREE）在细颗粒组分中较高，并随着粒度增大而减少，然而，ΣREE值随深度的变化与细颗粒含量（〈2μm粒级）仅微弱相关，与粗颗粒含量（〉32μm粒级）变化也不存在明显的相关关系，但与反映西风环流风力搬运强度的Zr/Rb值良好相关，可能暗示着昭苏波马黄土中REE含量的变化主要记录了西风环流强度和路径的改变而引起的水汽与物质的变化，因而ΣREE值能较好地阐释西风环流的变化以及这种变化所反映的气候环境演变。根据ΣREE值在剖面中的变化特征，结合粒度、Zr/Rb等指标，伊犁地区末次冰期以来的气候演化可以划分为4个阶段：80-57ka B.P.气候由温暖湿润逐渐变为寒冷干旱；57-28ka B.P.气候温暖稳定，降水比之前略有增多；28-8ka B.P.气候寒冷湿润；8ka B.P.至今气候整体温暖，但较为干旱。伊犁地区整个时期的气候变化大体上可与太阳辐射在亚轨道尺度上的变化呈现良好的相关。The westerlies lie in a transitional zone between two major climate systems of the north high latitude Hemisphere and the East Asian monsoon. Therefore, detailed studies on the evolution of the westerlies are key to investigating the past atmospheric circulation patterns, and hence to getting better understanding on the climatic forcing mechanism. The Ili Basin in the Xinjiang Province of Northwestern China is located in the Central Asian hinterland. The westerlies prevail this area perennially. Therefore, its widespread loess deposits in the alluvial terraces and piedmonts play an important role in understanding the evolution of climate change and atmospheric circulation in the westerlies. Considerable attentions have been attracted to loess deposits in the Ili Basin, especially on their origins, distribution, geochronology, magnetism and geochemical characteristics. However, the paleoclimatic significances of climatic proxies such as magnetic susceptibility and grain size remain unclear. Therefore, the evolution of climate change reconstructed from the loess deposit in the Ili Basin remains ambiguous, suggesting more studies with more proper proxies. In this paper, a typical loess/paleosol sequence（Zhaosu Poma section）from the Ili Basin has been chosen, and REE analysis is conducted to explore the climate change in this area since the Late Pleistocene. The Zhaosu Poma section（ZSP：42.69°N, 80.25°E; elevation 1875m）is located in the second terrace of the Tekes River in the south Ili Basin. It is 6.85m thick and totally five pedostratigraphic units（S0, L1L1, L1S1, L1L2 and S1）can be identified. OSL dating show that the age of the bottom of this section is nearly 80ka B.P. The sub-samples for REE analysis were taken at 5cm intervals through the section and totally 138 samples were collected. Some typical samples were selected for size-differentiated REE analysis. The results show that ΣREE values of ZSP are higher in fine particle sizes, and decrease with the increasing of particle size. However, t

关 键 词：西风环流 伊犁黄土 稀土元素 古气候 

分 类 号：P534.63[天文地球—第四纪地质学] P595[天文地球—古生物学与地层学]