Late Pleistocene Climatic Variations at Achenheim, France, Based on a Magnetic Susceptibility and TL Chronology of Loess
Late Pleistocene Climatic Variations at Achenheim, France, Based on a Magnetic Susceptibility and TL Chronology of Loess
复制标题
基于磁化率和黄土 TL 年代学的法国阿亨海姆晚更新世气候变化
作者：
D. Rousseau;L. Zöller;J. Valet
对Achenheim序列(法国阿尔萨斯)进行的新的野外调查可以描述上一个气候周期的大部分时间，即过去13万年来低场磁化率的变化。新的地层学数据和热释光测量使以前对阿琴海姆上更新世的年代学解释得以重新评估。对磁化率的高分辨率分析揭示了最近在另一段中发现的细粒“标志性”层位的存在。这一层位被解释为在黄土主要沉积阶段之前沉积的小尺度沙尘层。层位沉积在海相同位素阶段(MIS5/4)边界，在其他黄土层序中也发现过，在中欧尤为普遍。它的特点是磁化率低，颜色呈灰色。新的热释光年龄表明，黄土沉积发生在MIS5/4分界线之后，即7万年之后。这些结果与格陵兰GRIP冰芯尘埃记录一致，该记录也显示了72,000年前之后的尘埃大气。在更大的区域尺度上，Achenheim黄土序列表明欧亚黄土带西侧与格陵兰冰芯的尘埃记录之间存在可靠的相关性。
New field investigations of the Achenheim sequence (Alsace, France) allow for the characterization of variations in the low-field magnetic susceptibility over most of the last climatic cycle, i.e., the past 130,000 yr. New stratigraphic data and thermoluminescence measurements permit reassessment of the previous chronological interpretation of the Upper Pleistocene at Achenheim. A high-resolution analysis of magnetic susceptibility discloses the occurrence of a fine-grained “marker” horizon which was also found recently in another section. This horizon is interpreted as a small-scale dust layer deposited prior to the main interval of loess deposition. The horizon, deposited at the marine isotope stage (MIS) 5/4 boundary, has been found in other loess sequences and is especially prevalent in central Europe. It is characterized by low susceptibility values and a grayish color. New thermoluminescence dates indicate that the loess deposition took place after the MIS 5/4 boundary, i.e., after 70,000 yr. These results are consistent with the Greenland GRIP ice-core dust record which also demonstrates a dusty atmosphere after 72,000 yr ago. On a more regional scale, the Achenheim loess sequence demonstrates a reliable correlation between the western side of the Eurasian loess belt and the dust record of the Greenland ice cores.