下蜀黄土中记录的氧同位素3阶段(MIS3)特殊暖湿现象

THE ESPECIALLY WARM AND WET DURING MIS3 RECORDED BY XIASHU LOESS

下蜀黄土在第四纪古气候研究上具有独有的区位特征,对南京李家岗下蜀黄土剖面上部的近20m进行野外观察和室内研究,划分出5层黄土和5层古土壤,按5cm间距采集了Rb/Sr、色度、磁化率和粒度样品,并在剖面和可追索的相邻剖面上采集了12个光释光测年样品。通过气候代用指标与深海氧同位素及古里雅冰芯、马兰黄土等的对比,结合光释光测年,对南京李家岗下蜀黄土进行气候地层划分,对比结果将下蜀黄土划分出分别相当于MIS2～MIS5的4个气候旋回。气候意义的分析表明,各代用指标具有良好的可对比性,显示了氧同位素3阶段明显的特殊暖湿特征,并且其所反映的气候变化过程和强度与青藏高原及西部黄土具有明显的差异。

The Lijiagang Xiashu profile in Nanjing is a unique area for Quaternary research. Samples were taken from the file with an interval of 5 cm for measuring geochemical proxy, brightness, color reflector, magnetic susceptibility and granularity. And the climate stratum during 20 - 120 ka BP was divided into 5 strata of loess and 5 strata of paleosol by comparison of its multi-climate proxies with other records, such as high resolution oxygen isotopic records of marine and Guliya ice core, magnetic susceptibility of Malan loess. Luminescence dating technique was also adopted in this study, distinguishing 4 climatic cycles, corresponding to the MIS2 - MISS. And the stage corresponding to MIS3 was especially warm and wet, demonstrating its signifi- cant difference from the Tibet Plateau and the loess in West China in process and intensity of the climatic change. It＇s indicated that the ocean warming plays an important role on the East Asian monsoon area.