临汾盆地黄土沉积记录的MIS3气候变化

MIS3 climate change assessed according to loess deposition in the Linfen Basin,China

关于MIS3阶段的气候问题目前仍没有完全解决,需要更多区域的沉积记录分析。黄土被公认为第四纪气候研究的优秀载体,选择黄土高原东南缘的临汾盆地为研究区,通过对该区黄土沉积物磁化率、全铁、总有机碳和粒度系统研究,结合光释光年代学数据,初步讨论了MIS3阶段临汾盆地气候变化特征。MIS3阶段临汾盆地气候变化可分为3个阶段:56~45 ka BP气候为弱温湿,对应于MIS3c;45~41 ka BP呈现短暂的冷干,对应于MIS3b;41~25 ka BP表现为较强的温湿,对应于MIS3a。MIS3阶段全球气候表现出相对温湿,但临汾盆地在MIS3气候波动与其他地质记录表现出一定差异,造成这种结果的原因可能是在北半球冰盖和地表接收太阳辐射量共同作用下,热量和水分在各区域配置不同,导致各区域间表现出较大的环境差异,具体的耦合机制还需开展进一步研究工作。

The Marine Isotope Stage 3(MIS3)climate problem has yet to be resolved;thus,further analysis of regional sedimentary records is needed.Loess is recognized as an excellent carrier of quaternary climate research.This study investigated the climate characteristics and changes in the Linfen Basin during MIS3 based on optically stimulated luminescence dating and measurements of magnetic susceptibility,total iron,total organic carbon,and particle size in a profile near the 54:100 site of the Dingcun palaeoanthropological site.Results suggested that climate change in the Linfen Basin during MIS3 can be divided into three stages:56-45 ka BP,a weak-humid climate interval corresponding to the early stage of MIS3(MIS3c);45-41 ka BP,a short dry-cold interval corresponding to MIS3b;and 41-25 ka BP,a strong warm-humid interval corresponding to MIS3a.Comparative analysis of contemporaneous heterogeneous climate records from different regions throughout the world suggest that the climate of the Linfen Basin over MIS3 was generally warm and humid,although not as warm and humid as in the last interglacial period,which is consistent with other geological records.The significant regional variation in climate characteristics throughout the Linfen Basin over this time may be explained by the interaction between changes in the Northern Hemisphere ice sheet and solar radiation levels,respectively,rather than by regionally varying local drivers.These two mechanisms would have resulted in uneven distributions of heat and humidity throughout the region;thus,they can partly explain the regional differences observed in the data.However,the specific coupling mechanisms for these driving forces require further research.