陇西黄土沉积记录反映的末次间冰期以来青藏高原东北部季风的演化过程  

Process of monsoon variations of the northeastern Qinghai-Xizang Plateau from the loess record of Lonxi Basin since the last interglacial epoch

作　　者：杨东[1] 焦金鱼[1] 田娜[1] 方小敏[2] 李吉均[3] 

机构地区：[1]西北师范大学地理与环境科学学院,兰州甘肃730070 [2]中科院青藏高原研究所,北京100085 [3]西部环境教育部重点实验室＆兰州大学资源环境学院,兰州甘肃730000

出　　处：《干旱区地理》2008年第1期23-30,共8页Arid Land Geography

基　　金：教育部重点项目(05JJDZH234);国家自然科学基金项目(40473006);甘肃省自然科学基金(3ZS051-A25-009);西北师范大学自然地理学省级重点学科资助

摘　　要：对黄土高原西部的陇西盆地中断岘黄土剖面地层中的磁化率、粒度、CaCO3含量和有机碳含量等气候代用指标进行了综合分析。研究表明,青藏高原东北部地区在末次间冰期以来,其冬、夏季风的变化分别经历了多次相对增强的时期;其演化阶段基本可与深海氧同位素曲线(SPEC-MAP)对比,并且与同期的印度洋季风强度变化存在着较高的一致性。由此可以认为,全球冰量变化可能不是控制青藏高原季风演变的决定因素,而其它因素如太阳辐射变化及高原下垫面状况对高原季风演化可能具有更为重要的意义。Duanxian loess section of 40m thick is located at the seventh terrace of the Huanghe River, a pediment Longxi Basin lying to the west of the Liupanshan Mountains in the northeastern Qinghai-Xizang the ^14C and TL age dating from six paleosol horizons and five loess layers which were found in it was estimated that the bottom of the section is at the boundary between MIS 5 and 6, and it Plateau. According to the Duanxian section, can be compared with S1 in the Loess Plateau. Magnetic susceptibility, CaCO3 content and total organi proxies of summer monsoon changes and grain size as proxy of winter monsoon. quence in Duanxian were measured. Their variations show that the northeastern c carbon content are widely used as These proxies of a loess-paleosol separt of the Qinghai-Xizang Plateau experienced 5 times of enhanced winter monsoon and 6 times of enhanced summer monsoon periods, respectively,since the last interglacial epoch. Although the variation of the the oxygen isotopic stages in deep sea, outstanding difference in interglacial epochs in northeastern Qinghai-Xizang good correlation between variation of monsoon in in similar forcing factors. Therefore, the results Qinghai-Xizang Plateau monsoon can be compared with exists between them. The strength of summer monsoon Plateau is not always stronger than that in glacial epochs. The the plateau and the Indian Ocean monsoon suggested linkage of them to conclude that changes of the Qinghai-Xizang Plateau monsoon may not be controlled by the change of global ice volume. On the contrary, orbital forcing might be responsible for climate changes in the northeastern Qinghai-Xizang Plateau since at least the last interglacial epoch.

关 键 词：青藏高原 陇西黄土沉积 季风 演化 

分 类 号：P532[天文地球—古生物学与地层学]