萨拉乌苏河流域MGS2层段主要氧化物变化及其指示的气候波动

Primary Oxides Change in MGS2 in Salawusu River Valley and Indicated Climatic Change

萨拉乌苏河流域与MIS2相同时代的MGS2地层段记录了5.5个由风成砂与河流相或湖沼相构成的沉积旋回,通过对各沉积旋回的主要氧化物分析表明:河湖相中Al2O3、TOFE、K2O、MgO、CaO、Na2O、TiO含量通常明显高于风成砂,而SiO2含量则呈现相反的变化,构成了与沉积旋回相对应的5.5个主要氧化物变化旋回。结合各主要氧化物的化学迁移特性和剖面所在区域的地貌特征进行分析,认为该剖面的主要氧化物变化旋回是气候波动的反映,一个主要氧化物含量变动旋回指示了一个干冷暖湿旋回,也即一个冬夏季风先后演替的气候旋回。MGS2持续的时间仅为12ka,一个冬夏季风环境的变化大致平均仅需要2ka,一个冬季风或者夏季风环境的平均持续时间大约1ka。显然,这是一个千年尺度的环境变化。研究还表明,MGS2气候波动与晚冰期气候变化以及相关的Heinrich事件具有良好的对应关系。可以推断,MGS2记录的千年尺度环境变化是全球环境变化在本区域的反映。

There are 5.5 sedimentary cycles of aeolian sediments and fluvio-lacustrine sediments in MGS2 strata in Salawusu river valley. The primary oxides in these sediments are analyzed in this paper. The results show there are 5.5 oxide cycles corresponding with the sedimentary cycles, and the contents of A1203, TOFE, K20, MgO, CaO, Na20 and TiO in the fluvio-lacustrine sediments are higher than those in the aeolian sediments, while the content of SiO2 presents the reverse. Analysis of the chemical migration of primary oxides and the geomorphic feature of the research area indicate that these sedimentary cycles or oxide cycles are the reflection of climatic change in this area, and a sedimentary cycle or its corresponding oxide cycle indicates a cold-dry/warm-wet cycle, namely a alternation between winter monsoon and summer monsoon. As MGS2 continues only for 1 200 years, so one alternation between winter monsoon and summer monsoon continues for about 2 000 years and one winter monsoon or summer monsoon continues about only 1 000 years. Obviously, it is a millennium-scale environmental change. The good correlation between the climate change based on the sedimentary cycles and the primary oxide cycles in MGS2 with the climate change in last glacial period in North Europe and the tteinrich events indicates that the millennium-scale environmental change in MGS2 may be the region reflection of global environmental change.