川西高原黄土记录的末次冰期气候变化

川西高原位于高原气候区和季风气候区的过渡位置，该地区的气候特征对于认识青藏高原对周边气候的影响具有重要意义。通过对漳腊黄土剖面的¹⁴C年代测试、地层对比，结合粒度-年龄模型建立了剖面的年代序列。测试了粒度、色度、磁化率和碳酸盐等指标，建立了剖面的气候演化序列。结果表明，剖面记录了104 ka以来的气候变化过程。漳腊黄土粒度在MIS（深海氧同位素阶段）3和MIS4阶段的中值粒径接近，分别为17.6 μm和17.7 μm，反映了期间有一次高原隆升。漳腊黄土粒度曲线记录了多个粒度变粗和变细事件，粒度在H（海因里希）2时明显粗于H1，表明受到了高纬气候系统的影响。另外还存在2个明显的粒度变细事件，分别发生在处于MIS3的28~31 ka和42~45 ka，是低纬气候系统影响的结果。漳腊黄土研究结果表明川西高原气候系统影响因素的复杂性。

Loess Recorded Climatic Change During the Last Glaciation on the Eastern Tibetan Plateau, Western Sichuan

The western Sichuan Plateau is located on the transitional zone of plateau climate and monsoon climate. Climatic characteristics of this region are very important for understanding of the Tibetan Plateau impacting on the surrounding climate.¹⁴C dating, stratigraphic correlation and grain size vs. age model were used to calculate ages for all sampling stratigraphic levels. Multi-proxy including grain size, color, magnetic susceptibility, and carbonate content analysis of Zhangla loess section at western Sichuan Plateau revealed a detailed history of climate changes since 104 ka B.P. The long-term trend of increasing grain size, middle grain sizes are 17.6 and 17.7 μm in MIS(marine isotope stage)3 and 4, may be explained in part by a rapid uplift of the Tibetan Plateau events. The climate showed sub orbital scale fluctuations similarity to millennial-scale climatic changes recorded in Nanjing stalagmite. The strength of H(heinrich)2 significantly higher than H1. It may indicate that the climate system at high latitudes in the Northern Hemisphere had played an important role. There were two distinct weakening aridification recorded in MIS3, during 28-31 ka and 42-45 ka. They may suggest that the climate system also controlled by factors at low latitudes.