藏西北结则茶卡湖晚更新世以来演化及气候环境  

EVOLUTION OF JIEZECHAKA LAKE AND THE CLIMATIC ENVIRONMENT OF THE LATE PLEISTOCENCE IN NORTHWEST TIBET

作　　者：杨俊峰[1] 崔霄峰[1] 卢书炜[1] 李秋生[1] 

机构地区：[1]河南省地质调查院,河南郑州450007

出　　处：《新疆地质》2005年第1期59-63,共5页Xinjiang Geology

摘　　要：结则茶卡位于藏北高原湖盆区西北部,喀喇昆仑山与昆仑山交汇部位的西南侧,处于班公湖—怒江结合带与红其拉甫—双湖结合带之间,湖面海拔高度4525m.在其拔湖325m附近明显存在一条高位湖岸线,从该湖岸线到湖面,发育了各级较为连续的湖积阶地和众多保存较好的湖岸堤、湖蚀槽、湖蚀柱和湖蚀台地.沿湖岸不同高度上的湖积物U系年龄分别为(14.2±1.2)kaB.P.(T2)、(38.0±3.5)kaB.P.(T4)和(41.6±3.2)kaB.P.(T5),根据湖面下降幅度推算出结则茶卡高位湖积层形成年龄大致在120~90kaB.P..晚更新世以来结则茶卡处于封闭演化体系中,湖泊的萎缩主要与气候干旱、少雨有关,湖面平均退却速度3.31mm/a.大约晚更新世初期,青藏高原存在着一个高湖面,大致在100kaB.P.开始,青藏高原泛湖期从西向东逐渐结束,其气候也从西向东可能逐渐变为干旱、少雨.Jiezechaka Lake is located in the northwest part of the lacustrine basin area in the tableland of North Tibet, southwest of the juncture of the Kalakunlun and Kunlun mountains. The lake formed at the link position of Bangong Lake-Nu river and the Hongqilapu-Double river. The altitude of the lake surface is 4 525 m. There is a distinctive perch lake shoreline at 325 m above the lake. From this shoreline to the lake-surface, there occurs a lacustrine deposit terrace and numerous lake shore banks, lake erosion grooves, lake erosion poles and lake erosion mesas which are all well preserved. U system ages of the lacustrine sediments at different altitudes are: (14.2±1.2) ka B.P.(T2)、(38.0±3.5) ka B.P.(T4) and (41.6±3.2) ka B.P.(T5). According the extent of the lake surface descend, it reckons that the forming The age of the Jiezechaka lacustrine sediments is estimated to be about 110 ka^120 ka B.P from the rate the lake surface has descended. Since the Late Pleistocence, the Jiezechaka Lake is a block out evolvement system. The dropping lake level is related to an arid climate and lack of rain. The descent of the lake surface (325 m) is larger than Namucuo Lake (139.2 m). The speed of the descent of the lake surface is approximately 3.31 mm/a. In the initial stages of the Late Pleistocence the lake existed as a high lake surface in the Qingzang Altiplano. About 100 ka B.P, the flooding period of the Qingzang Altiplano gradually ceased from west to east. The climate also changed, becoming dryer from west to east.

关 键 词：晚更新世 气候环境 演化 茶 青藏高原 喀喇昆仑山 藏北高原 海拔高度 形成年龄 气候干旱 结合带 西北部 班公湖 湖岸 湖积物 湖积层 高湖面 高位 少雨 湖盆 交汇 阶地 台地 下降 

分 类 号：P534.63[天文地球—第四纪地质学]