西昆仑山区湖泊初探

LAKES IN THE WESTERN KUNLUN MOUNTAIN AREAS

本文论述了西昆仑山区湖泊的分布、成因、水化学特征以及其演化历史与高原隆升、古气候变化、高山冰川进退之间的关系。研究结果表明,该区湖泊主要靠暖季高山带的冰雪融水补给,故矿化度的变化与其距补给源的远近密切相关;它们在第四纪期间的演化是高原构造隆升和全球气候变化二者作用的结果;根据现有资料,该区湖泊的演化历史可大致分为3个阶段,即距今4.6万年以前的大湖期,晚更新世晚期的湖面波动期和全新世的湖泊退缩期。

This paper discussed the relationship between the distributions, geneses, water chemical characters and evolutionary history of the lakes in the Western Kunlun Mountain areas, and the uplift of the Qinghai-Xizang Plateau, paleoclimatic changes, advance and retreat of the alpine glaciers.Water supply of the lakes depends mainly on the meltwater of alpine snow and ice during the warm season. Therefore, the change of the salinity of lake water is directly related to the distance from the supply source to the lake. With changing of the lake types from freshwater to saltwater to saline, the contents of HCO7 and Ca2+ are clearly decreasing, and Cl- and Na+ increasing. In addition, in freshwater lakes, the absolute contents of HCO3- and Ca2+ are obviously becoming higher with increase in the salinity of the lake. In saltwater and saline lakes, it is shown that the absolute contents of Cl- and Na+ are clearly becoming higher with the increasing of salinity.The evolution of the lakes during the Quaternary is the result of coaction of the tectonic uplift of the plateau and the global climatic changes. It can be divided to three main stages: viz., 'Great Lake Period' before 46 000 a B.P.; 'Lake-level Fluctuation Period' in the later stage of the Late Pleistocene, during this period, the great lake existing in the first stage disappeared and several small lakes were formed after 46 000 a B. P. Up to about 36 000 a B.P., a high lake-level appeared, which corresponded to the interstadial of the last glaciation. Another high lake-level appeared in the time from 21 000 a B.P. to 15 000 a B.P., about 40 m higher than the present day lake-level; and 'Lake Shrinking Period' in the Holocene.