中原邙山黄土与末次间冰期以来古季风特征

The Mangshan Loess in Central China and Paleomonsoon Characteristicsince the Last Interglacial Stage

中原邙山赵下峪剖面出露S10以上黄土地层,厚度大于172.1m。末次间冰期S1古土壤厚15.7m,末次冰期L1黄土厚达77.3m,其中晚冰阶L1LL1黄土、间冰阶L1SS1古土壤和早冰阶L1LL2黄土分别厚41.6m、13.2 m和22.5 m。邙山黄土是厚度最大的晚更新世黄土地层剖面之一,记录了丰富的气候环境变化信息。用SPECMAP氧同位素曲线确定的阶段界限的日历年龄为标定点和磁化率年龄模式,获得相应的时间标尺,据以计算出S2以上各层段的平均沉积速率和分辨率。邙山黄土倒数第二间冰期以来不同冰期或冰阶与间冰期或冰阶的粒度、平均沉积速率和分辨率有很大的差异,其中以末次冰期晚冰阶L1LL1黄土的平均沉积速率为最高,达3.45 mm／a,而末次问冰期S1古土壤的沉积速率亦高达0.28 mm／a。本文主要根据赵下峪剖面的磁化率和>45μm粗颗粒含量变化曲线,并与格陵兰GRIP冰心和深海SPECMAP氧同位素曲线对比,讨论末次间冰期以来古季风特征及其相互关系。

The Mangshan Yuan is a loess platform on the southern bank of the Yellow River, which is located in northwestern Zhengzhou of Henan Province, China. The typical Zhaoxiayu section of the Mangshan Yuan preserves stratigraphical loess units above S10 with a total thickness of 172. 1 m, which includes 15. 7 m of .the last interglacial paleosol S1, 77. 3 m of the last glacial loess L1 that consist of 41. 6 m of the late stade L1LL1, 13. 2 m of the interstade L1SS1 and 22. 5 m of the early stade L1LL2. Based on the age marking points by correlating magnetic susceptibility of the section with the SPECMAP curve, the timescale of the section was constructed, and the average accumulation rate and the resolution of each loess strata over the S2 were subsequently calculated using the susceptibility age model. The results indicate that strata units developed in the glacial, interglacial stages, stadial and interstadial show substantial differences in grain size, average accumulation rate and time resolution in the Zhaoxiayu section. Specifically, the average accumulation rate of the loess L1LL1 is 3. 45 mm/a, whereas that of paleosol S1 is only 0. 28 mm/a. Based on the high - resolution records of magnetic susceptibility and >45 μm fraction percentage of the loess - paleosol, the summer and winter monsoon variations as well as their interrelations since the last interglaciation have been discussed, which were correlated with the SPECMAP and the GRIP climate records.