S2以来下蜀黄土沉积序列磁化率记录与深海氧同位素记录的对比

对镇江下蜀黄土剖面进行了系统的磁化率测试，并同深海氧同位素记录进行了对比。结果表明，S2以来下蜀黄土磁化率记录与深海氧同位素记录存在良好的对应关系。首次在下蜀黄土记录中发现了相当于深海氧同位素5a,5b,5c,5d和5e亚阶段的波动特征；下蜀黄土S2磁化率记录则可与深海氧同位素7阶段进行细节上的详细对比。对比揭示，最近20多万年以来，下蜀黄土堆积区对全球古气候变化有着积极的响应；同时，下蜀黄土记录的古气候变化在某些阶段又具有明显的区域特征，可能反映的是全球气候变化效应与东亚古季风气候影响的叠加作用。镇江下蜀黄土剖面能获得精度较高的全球变化信息与其特定的地理位置、纬度位置和地貌条件有关。

Magnetic Susceptibility Records of the Xiashu Loess Since S2 and Their Comparisons with the Marine Oxygen Isotope Records

As a paleo-climatic proxy index, magnetic susceptibility (MS) parameter, which has been widely used in loess studies of northern China, is applied in studies on the Xiashu loess in the south of lower reaches of the Yangtze River. On the basis of systematic sampling and measurement, we obtain magnetic susceptibility curve of the Xiashu loess in Zhenjiang and compare it with marine isotope stages (MIS). The result shows that the magnetic susceptibility records of the Xiashu loess since S2 stratum coincide perfectly with marine isotope records since stage 7. Paleosol S0 of the Xiashu loess shows high magnetic susceptibility value and can be compared with MIS-1, representing a high temperature period. The MS curve of loess L1 displays 3 valleys (L1-1, L1-3 and L1-5) and 2 peaks (L1-2, L1-4) alternately. L1-1 and L1-5 can be compared with MIS-2 and MIS-4 respectively. L1-2, L1-3 and L1-4 can be compared with MIS-3 on the whole. The MS curve of Paleosol S1 shows the peak shape on the whole. The curve during this period can be divided into 3 sub-peaks (S1-1, S1-3 and S1-5) and 2 sub-valleys (S1-2, S1-4), which can be compared with MIS-5a, 5c, 5e, 5b and 5d respectively.This indicates that there exist 2 cold-dry variations under the hot-wet background during the last inter-glacial epoch. This is the first time to find the change feature corresponding to MIS-5a, 5b, 5c, 5d and 5e in the Xiashu loess records, but the change details contain certain differences between MS records of the Xiashu loess and MIS records. The MS curve of loess L2 shapes as a valley on the whole. It contains 2 sub-valleys and 1 sub-peak in detail, which can be compared with MIS-6, reflecting a cold-dry climate as a whole and 1 hot-wet variation in it. The MS curve of Paleosol S2 coincides perfectly with MIS-7. It is similar to that of Paleosol S1 and consists of 3 sub-peaks (S2-1, S2-3 and S2-5) and 2 sub-valleys (S2-2, S2-4). Its change feature reveals 3 hot-wet and 2 cold-dry variation alternately during the penultimate interglacial epoch. The comparison between magnetic susceptibility records of the Xiashu loess and marine oxygen isotope records indicates that the area of the Xiashu loess deposition has given a sensitive response to globe paleo-climatic changes since about 200 kyr. BP. On the other hand, the climate changes in some stages recorded by the Xiashu loess has regional characteristics obviously, which might be the result of the dual effect of globe climate changes and East-Asia monsoon climate changes. The Xiashu loess section in Zhenjiang containing globe change information with high precision should be related to its geographic position, latitude location and landform conditions.