末次间冰期陇西黄土记录与气候不稳定性问题的初步研究

陕西黄土高原黄土记录的分辩率较高，Ｓ１古土壤厚达８．５ｍ，主要由两个古土壤组和其间黄土层组成。临夏塬堡剖面上可分为５个古土壤层，主要黄土层记录了末次间冰期内的较干冷高粉尘堆积时期。

A Preliminary Study on Longxi Loess Record during the Last Interglacial Period and the Problem of Climatic Instability

The Longxi basin is one of the main centres of aerial dust deposition in China, where the loess record has a quite high resolution. Paleosol S 1 is up to 8.5 m thick in the region. It is consists of two paleosol groups(S 1S 1 and S 1S 2) and the loess S 1L 1 between them which recorded the main dust deposition period. There are five paleosol S 1 layers at Yuanbao section in Linxia basin, Gansu. It is shown by short term magnetic susceptibility data, CaCO 3 content, grain size data and soil micromorphology result that the three paleosol layers of paleosol group S 1S 2 have a stronger pedogenesis than paleosol group S 1S 1. The best developed paleosol layer is the one at the beginning of S 1S 2. There are nearly no calcite fragments in micromorphologyically thin sections. The main vegetation in the period was broad leaf forest and grass with a high content of subtropical trees. The climate during the soil formation was warmer than the present. The paleosol S 1S 2S 2 was also strongly developed, but it is coarser than other S 1 paleosol layers, showing that there were high dust depositions in its formation. Paleosol S 1S 2S 1 development is nearly the same as that of paleosol S 1S 2S 3. Two main high dust deposition periods are identified in thin sections of soil morphology. There are two possible correlations between paleosol S 1 layers and the substages of deep sea stage 5 because of dating problems. It is clear, however, that the substage 5e recorded by paleosol S 1 in Longxi loess was not a stable and continuous warm period whatever correlations were used.