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引用本文:朱大岗1 孟宪刚1 赵希涛2 邵兆刚1 杨朝斌3 马志邦2 吴中海1 王建平1. 西藏纳木错和藏北高原古大湖晚更新世以来的湖泊演化与气候变迁[J]. 中国地质, 2004, 31(3): 269-277.
ZHU Da-gang1, MENG Xian-gang1, ZHAO Xi-tao2, SHAO Zhao-gang1, YANG Chao-bin3, MA Zhi-bang2, WU ZHONG-hai1, WANG Jian-ping1. Evolution and climatic change of Nam Co of Tibet and an ancient large lake in the northern Tibetan Plateau since the late Pleistocene[J]. Geology in China, 2004, 31(3): 269-277(in Chinese with English abstract).
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西藏纳木错和藏北高原古大湖晚更新世以来的湖泊演化与气候变迁
朱大岗1 孟宪刚1 赵希涛2 邵兆刚1 杨朝斌3 马志邦2 吴中海1 王建平11,2,3
1.中国地质科学院地质力学研究所,北京 100081;2.中国科学院地质与地球物理研究所,北京 100029;3.西藏自治区国土资源厅,西藏 拉萨 850000
摘要:
提要: 根据野外水准测量与室内实验分析,本文探讨了西藏纳木错和藏北高原古大湖晚更新世以来的湖泊演化和气候变迁。在纳木错沿岸拔湖48 m以下,发育了6级湖岸阶地,拔湖48~139.2 m发育有高位湖相沉积。研究表明,纳木错湖泊发育与藏北高原东南部古大湖演化可划分为3个阶段:①116~37 ka B.P.间的古大湖期;②37~30 ka B.P.间的外流湖期;③30 kaB.P.以来的纳木错期。在古大湖阶段,包括纳木错、色林错和扎日南木错、当惹雍错等藏北高原东南部的一大批现代大、中、小型湖泊,都是互相连通的一个古大湖,其范围可能超过了现代的藏北内、外流(怒江)水系的分水岭。它或许还与藏北高原南部和西部的其他古湖相连,成为统一的藏北高原“古大湖”。通过对纳木错湖相沉积形成时代与深海氧同位素对比,易溶盐、pH值、地球化学、介形类和孢粉分析等的综合研究发现,湖相沉积记录了自晚更新世以来的湖泊演化和气候变迁信息。资料显示古大湖期湖面最高,气候温和清爽;外流湖期湖面急剧下降,气温和湿度较现今略高;纳木错期以来气候经历了全新世最宜期的暖湿后日益干旱化,气温波动,湖面持续下降。表明自晚更新世以来该区气候在逐渐变干的总趋势的基础上,经历了多次明显的冷暖与干湿波动。
关键词:  西藏纳木错  晚更新世  湖泊演化  气候变迁  古大湖
DOI:
分类号:
基金项目:中国地质调查局地质大调查项目(DKD2001006、DKD9901001)资助。
Evolution and climatic change of Nam Co of Tibet and an ancient large lake in the northern Tibetan Plateau since the late Pleistocene
ZHU Da-gang1, MENG Xian-gang1, ZHAO Xi-tao2, SHAO Zhao-gang1, YANG Chao-bin3, MA Zhi-bang2, WU ZHONG-hai1, WANG Jian-ping11,2,3
1. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China;2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;3. Land and Resources Department of the Xizang (Tibet) Autonomous Region, Lhasa 850000, China
Abstract:
Abstract:The paper discusses the Evolution and climatic change of Nam Co of Tibet and an ancient large lake in the northern Tibetan Plateau since the late Pleistocene based on the field leveling survey and laboratory analysis. There are 6 lake terraces along the lake shore of Nam Co less than 48 m above the lake level and highstand lacustrine sediments 48 m to 139.2 m above the lake level. Research shows that the development of Nam Co and evolution of the ancient large lake in the southeast of the northern Tibetan Plateau underwent three stages: ① The ancient large lake stage at 116—37 ka BP, ② the outflow lake stage at 37—30 ka BP, and ③ the Nam Co stage since 30 ka BP. In the ancient large lake stage, a large number of large, medium-sized and small, modern lakes in the southeast of the northern Tibetan Plateau such as Nam Co, Siling Co, Zhari Namco Co and Tangra Yumco were joined together to form a single great lake, whose areal extent might overstep the watershed between the northern Tibet endorheic drainage system and exorheic drainage (Nujiang River) system. It might also be joined with other ancient lakes in the south and west of the north Tibetan Plateau, forming a unifying “ancient large lake”in the northern Tibetan Plateau. Through the comparison between the ages of the lacustrine sediments of Nam Co and the deep-sea oxygen isotope records and an integrated study of more soluble salts, pH values, geochemistry and ostracods and sporopollen, the authors have found that the lacustrine sediments record the information of lake evolution and climatic change since the late Pleistocene. Data show that: during the ancient large lake stage the lake level was the highest and the climate was mild and slightly dry; during the outflow lake stage the lake level lowered sharply and the air temperature and humidity were slightly higher than the present; and the climate got arid increasingly, temperatures fluctuated and the lake level dropped continuously after the warm and humid climate in the Holocene Climatic Optimum since the Nam Co stage. Based on the general trend of getting arid gradually, the climate in the region experienced several marked cold-warm and dry-humid fluctuations since Late Pleistocene.
Key words:  Nam Co, Tibet  late Pleistocene Epoch  lake evolution  climatic change  ancient large lake