青藏高原北缘末次冰期最盛时期的湖侵及其原因

Lake Transgression and Reasons during Last Glaciation Maximum on the North Margin of Qinhai-Xizang Plateau

近年的研究发现,青藏高原北缘众多的湖泊,在18000aB.P.前后均有明显的上升扩张现象,水位高出今日湖面10—40m不等,湖侵开始与结束的时间,西部稍早于东部。盛冰期湖侵与冰雪融水的增加、湖面蒸发量的减少、西风带的移动以及土壤水分收支的节余等因素有关,该湖侵层的发现对认识和评估青藏高原在全球环境变化中的作用和地位具有重要的理论意义。

Recently it has been discovered that many lakes on the north margin of Qinhai-Xizang Plateau had expanded during Last Glaciation Maximum, around 18 000 a B.P., and the lake level was 10-40 m higher than that at present. The lake transgression started and evded earlier in the west part than that in the east part of the plateau. The reasons of lake transgression during Last Glaciation Maximum are related to the increase of ice and snow melt-water in warm season and to the reduction of lake evaporation. The discovery of lake transgressional stratigraphy has important theoretioal significance for recorgnizing and evaluating the role of Qinhai-Xizang Plateau in Global environmental changes.