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| 黄土高原红粘土序列与晚第三纪的气候事件 | |
| 引用本文： | 安芷生,孙东怀,陈明扬,孙有斌,李立,陈宝群.黄土高原红粘土序列与晚第三纪的气候事件[J].第四纪研究,2000,20(5):435-446. |
| 作者姓名： | 安芷生 孙东怀 陈明扬 孙有斌 李立 陈宝群 |
| 作者单位： | 1. 中国科学院黄土与第四纪地质国家重点实验室，西安710054 2. 中国科学院地质与地球物理研究所，北京100029 |
| 基金项目： | 国家重点基础研究发展规划项目!G1999643401，国家自然科学基金!49823001 |
| 摘 要： | 红粘土序列由7个古土壤组合和与之相间的红色黄土组合组成，它们是建议的地层划 分和对比的一级单位。系统的古地磁研究表明，黄土高原风尘沉积开始的年龄约为7．2MaB．P．，它标志着晚新生代亚洲内陆干旱化的开始，可能意味着青藏高原在此时达到了有意义的高度，东亚古季风环流基本建立。风尘沉积速率与夏季风强度在长时间尺度上的耦合揭示了它们与青藏高原高度的共同联系，也意味着青藏高原可能经历了多次隆升和夷平过程；第四纪黄土-古土壤序列是2.6～2.8MaB.P．全球冰期-间冰期气候旋回建立的证据。 |
| 关 键 词： | 红粘土 古地磁 青藏高原隆升 |
| 收稿时间： | 2000-07-09 |
| 修稿时间： | 2000年7月9日 |
RED CLAY SEQUENCES IN CHINESE LOESS PLATEAU AND RECORDED PALEOCLIMATE EVENTS OF THE LATE TERTIARY |
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| An Zhisheng,Sun Donghuai,Chen Mingyang,SUN Youbin,Li Li,Chen Baoqun.RED CLAY SEQUENCES IN CHINESE LOESS PLATEAU AND RECORDED PALEOCLIMATE EVENTS OF THE LATE TERTIARY[J].Quaternary Sciences,2000,20(5):435-446. | |
| Authors: | An Zhisheng Sun Donghuai Chen Mingyang SUN Youbin Li Li Chen Baoqun |
| Institution: | 1. State Key Laboratory of Loess and Quaternary Geology, Chinese Academy of Sciences, Xi'an 710054; 2. Institute of Geology and Geophysics| Chinese Academy of Sciences, Beijing 100029 |
| Abstract: | Based on systematic geological investigation four sections of the Late Tertiary redclay sequence were chosen for the study of stratigraphy, paleomagnetism andpaleoclimatology. These sections are Lingtai, Bajiazui, Zhaojiachuan in the central part,Duanjiapo in the southem part of the Loess Plateau. Thermal demagnetizer andcryogenic magnetometer were used to systematically measure the magnetic remanencefrom room temperature up to 500 or 600℃ with 50℃ step in order to establishmagnetostratigraphy of the sections. The results show a consistent polarity structure.Magnetostratigraphy of the red clay sequence consists of normal polarity Chron ofGauss, reversed Chron of Gilbert. The Chron Gauss is characterized by a long normalpolarity with two reversed events at lower part of the Chron. Chron Gilbert can bedetermined by its polarity structure of two reversed sub-Chron which are separated by4 small normal events. All complete eolian sequence profile consistently suggest thebottom of red clay is within the Chron 3B, and the bottom age of the sequence isabout 7.2Ma B.P. The red clay sequence in Chinese Loess Plateau consists of 7paleosol complex (named RS1 to RS7) interbeded with 7 reddish pedogenic loesscomplex (named RL1 to RL7), which are the first order strata units for red clayclassification and comparison. Magnetic susceptibility was measured for all sections to reflect the East AsianSummer monsoon and the eolian accumulation rate is used as the indicator of thearidity of the source areas. The sediment in Loess Plateau marks the beginning ofinternal Asia continent drying, and probably imply that Tibet Plateau had reachedsome critical elevation and the related Asia monsoon had develop by 7.2Ma B.P.Coupled variation trend of the eolian accumulation rate and the summer monsoonintensity indicated by susceptibility suggest their dynamic link to the altitude of TibetPlateau, and hence their variations may suggest that Tibet Plateau experiences severaltectonic cycle of uplifting-erosion processes. The onset of global glacial-interglacialcycles at 2.6～2.8Ma B.P. greatly intensified the winter monsoon circulation andamplified paleoclimate variation amplitude represented by Quatemary loess-paleosolsequence. |
| Keywords: | red clay magnetostratigraphy Tibet uplift |
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