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兹格塘错是一个内陆封闭型湖泊,位于藏北高原腹地,处于西南季风作用边缘地带。由于流域内无冰川分布,湖泊补给主要靠大气降水,因此水体的扩张与收缩能够直接反映西南季风的变化。半干旱气候地区湖泊沉积物碳酸盐含量能够敏感地反映水体的扩张与收缩。兹格塘错沉积物碳酸盐含量高,与可溶盐(氯离子与硫酸根离子)含量变化结合能更好地揭示水体的演化阶段。分析结果表明,在9.3～8.9calkaBP、8.3～7.8calkaBP、5.0～4.7calkaBP、4.0～3.8calkaBP和3.1～2.7calkaBP碳酸盐含量出现大幅度下降,指示湖泊淡化、水位升高。但在3.8calkaBP左右碳酸盐含量和可溶盐(氯离子与硫酸根离子)含量同时出现峰值,指示出湖泊水体盐度升高、水位出现下降;近1calkaBP以来,碳酸盐与可溶盐含量都呈现逐渐下降趋势,表明湖泊水体逐渐淡化、水位缓慢上升的过程。但近100a来可溶盐含量上升,指示出湖泊水体的不断浓缩和水位下降过程,这和近百年的气候暖干化过程是一致的。兹格塘错沉积岩心碳酸盐含量全新世以来5次极低事件,有力地证明青藏高原西南季风在全新世期间的不稳定性。
Zugengtu is a hinterland closed lake, located in the hinterland of the northern Tibet Plateau, at the edge of the southwest monsoon. Because of the absence of glaciers in the basin, the recharge of lakes mainly depends on the atmospheric precipitation. Therefore, the expansion and contraction of the water body can directly reflect the changes of the southwest monsoon. Carbonate content of lake sediments in the semi-arid climate can sensitively reflect the expansion and contraction of water bodies. The high carbonate content in the Zugengtang sediments combined with changes in the contents of soluble salts (chloride and sulfate) can better reveal the evolutionary stage of the water body. The results show that there is a significant decrease in the carbonate contents from 9.3 to 8.9 calkaBP, from 8.3 to 7.8 calkaBP, from 5.0 to 4.7 calkaBP, from 4.0 to 3.8 calkaBP and from 3.1 to 2.7 calkaBP, indicating a desalination of the lake and an increase in water level. However, at the same time, the content of carbonate and soluble salt (chloride ion and sulfate ion) around 3.8calkaBP peak at the same time, which indicates that the salinity of lake water increases and the water level declines. Since the last 1calkaBP, carbonate and soluble salt The content showed a gradual downward trend, indicating that the lakes gradually dilute the water level, the water level rise slowly. However, the content of soluble salt increased in the past 100 years, indicating that the lake water continued to concentrate and the water level declining process, which is consistent with nearly a hundred years of climate warming and drying process. Five extremely low events since the Holocene Carbonate content in the Zgang fault sedimentary core strongly support the instability of the southwesterly monsoon over the Tibetan Plateau during the Holocene.