西藏羌北高原多格错仁盐湖中更新世晚期以来的环境演化记录

Environmental evolution recorded in a saline lake on the northern Qiangtang Plateau in Tibet since Late Middle Pleistocene

通过对西藏藏北高原多格错仁盐湖湖岸3101cm高度剖面进行地形地貌、地层沉积特征、矿物学特征及粒度、频率磁化率等气候环境变化指标的分析研究发现,整个剖面反映出大致6个较大的气候变化过程:233.3kaBP^223.5kaBP气候波动较大,总体趋势气候趋于干冷,期间出现过两次较温暖气候,之后气候逐渐变冷;在223.5kaBP^213.6kaBP总体变化为气温大幅度上升,但在期间有一次较大的相对冷干过程;213.6kaBP^170kaBP之间总体变化气候趋于变冷,中间有2次明显的气候变暖湿过程及两次冷干过程;170kaBP^117.1kaBP气候转为明显湿热;117.1kaBP^75.6kaBP气候变化趋势明显降低;75.6kaBP^56.7kaBP气候又明显上升达到湿热状态。以上气候波动规律与极地冰芯记录及深海氧同位素记录的古气候波动规律有很好的一致性,同时本盐湖区与柴达木盆地察尔汗盐湖区的CH0310钻孔及青海湖南岸二郎剑阶地的QH-86钻孔所揭示的中更新世晚期以来的气候变化的分析对比,发现西藏羌北的多格错仁盐湖区与青海的察尔汗盐湖区及青海湖湖区在更新世中晚期以来的气候环境变迁存在极好的可比性,说明青藏高原的气候演化在中晚更新世以来基本具有一致性,在时间上的微小超前与滞后具有区域上的细微变化,说明气候变迁在不同的区域又具有各自的独特性。

Investigation of environmental change indicators,and sedimentological,mineralogical and magnetic susceptibility studies on a 3101 cm high profile on the Dogai Coring salt lake shore,northern Tibet plateau,reveal six episodes of major climate change.These are(i)a general trend of cold and dry climate between 233.3~223.5 ka BP including two episodes of warmer climate followed by gradual climate cooling;(ii)a sharp increase in temperature between 223.5~213.6 ka BP;(iii)an overall colder climate between 213.6~170 ka BP that was interrupted by two warm and wet events;(iv)between 117.1 ka B.P.~75.6 ka B.P.the climate trended towards decreasing temperatures;and(vi)a hot and humid climate between 75.6~56.7 ka BP.Evidence of past climate variability and its periodicity has been preserved in polar ice cores and the deep sea oxygen isotope records.However,there is a contrast between the mid-Pleistocene palaeoclimate changes recorded in the Dongai Coring salt lake and the CH0310 borehole from the Qarhan saline lake in Qaidam basin and the QH-86 borehole on the south bank of Qinghai Lake.find that it is comparable with Qaidam basin salt lake and Qinghai lake on ancient climate change regularity.