【摘要】 藏南帕里地区发育有2级湖积阶地,前人对其Ⅱ级湖积阶地的形成时代存在争议。热释光测年结果表明,湖积Ⅱ级阶地形成于89～58kaBP,Ⅰ级阶地形成于约4kaBP。根据湖相地层的分布、沉积物特征和测年结果,将帕里地区湖泊发育划分为帕里湖期(89～58kaBP)、外流湖期(23～10kaBP)和多庆错湖期(10～2.5kaBP)3个演化阶段。Ⅱ级湖积阶地对应于帕里湖期发育阶段;外流湖期发育于末次冰期晚冰阶,以冰碛为主要特征,此时喜马拉雅山主脊带分水岭北移至现今荡拉山的位置;多庆错湖期形成了大型冲积扇(5.7～5.15kaBP)和湖积Ⅰ级阶地,湖面面积大幅度萎缩。2.5kaBP后藏南局部地区开始沙化,帕里地区湖体减少,呈现今天的面貌。更多还原

【Abstract】 Lacustrine deposits and two steps of lake terraces are developed in the Pagri area, southern Tibet. Divergent views exist as to the age of terrace II. Thermoluminescence (TL) dating shows that: terrace II formed at 89-58 ka and the terrace I at 4 ka. According to the distribution, characteristics and dating of the lacustrine deposits, the lake development in the Pagri area may fall into three stages: Pagri Lake stage (89-58 ka), overflow lake stage (23-10 ka) and Dogên Co stage (10-2.5ka). Terrace II corresponds to the Pagri Lake stage. The outflow lake stage, which is characterized by tills, occurred in the late glacial interval of the Last Glacial Maximum, when the watershed of the main ridge zone of the Himalayas shifted northward to the location of present Tangla Mountain. During the Dogên Co stage, large alluvial fans (5.7-5.15 ka) and terrace I formed and the lake surface shrank greatly. After 2.5 ka, the lake area in the Pagri area was reduced and desertification occurred in some places of southern Tibet. Then the area displays the present-day appearance.更多还原