贡嘎山东麓第四纪冰川作用与磨西台地成因探讨  

Study on the Quaternary Glaciation and the Formation of the Moxi Platform in the East Slopes of the Mount Gongga

作　　者：郑本兴[1] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所,甘肃兰州730000

出　　处：《冰川冻土》2001年第3期283-291,共9页Journal of Glaciology and Geocryology

基　　金：中国科学院寒区旱区环境与工程研究所知识创新工程项目(CACX2 10 0 10 )资助

摘　　要：青藏高原东部的最高峰贡嘎山 (海拔 75 5 6m)东麓磨西河流域发育了三次更新世冰期 ,分别为雅家埂、南门关、贡嘎冰期 ,其中燕子沟的倒数第二次冰期 (南门关冰期 )的冰川一直伸到磨西镇下街磨西饭店北 .古冰川阻塞主谷 ,在新兴与南门关沟之间的堡子坝区形成冰川阻塞湖 ,在磨西镇上街东 ,该期古冰川覆盖在谢家河坝东面山坡上 ,融水深切形成峡谷 .冰退过程中又在峡谷西基岩丘陵旁形成冰水湖 ,南门关冰期后的间冰期时 ,小湖变干发育了红色古土壤层 ,该期的红色古土壤层在磨西镇下街南的古冰川与冰川泥石流沉积层顶面也有保存 .证明磨西台地的主体为倒数第二次冰期的冰川堆积物 ,其中也包括有冰水砂砾层透镜体和冰湖相等沉积 .磨西台地出露地表的巨大砾石 ,直径在 10～ 2 0m之间 ,多数为冰川表面的消融碛 ,也可能有冰川泥石流夹带的大岩块 .磨西台地两侧断续分布有 4级冰水阶地以及磨西饭店以下的磨西台地尾部均为末次冰期后期至全新世的冰水沉积 ,其中也含有泥石流堆积物 .The Mount Gongga (7 556 m) is the highest peak in the east part of the Tibetan Plateau. Around the mount there are 74 glaciers, 255.10 km\+2 in area, among which 5 glaciers are over 10 km in length. The Hailuogou Glacier on the east slope of the mount is 13.1 km in length and 25.7 km\+2 in area, and extents to \{2 980\} m a.s.l. It is the longest maritime glacier in the Hengduan Mountains. The Yanzigou Glacier, nearby the Hailuogou Glacier, is 10.5 km in length and 32.15 km\+2 in area, and extends to \{3 680\} m a.s.l. In the Moxi River Basin, a basin on the east slopes, three Pleistocene Glaciations and three advances in the Neoglaciation, as well as the Little Ice Age, of the Holocene can be recognized. They are Yajiagen (Middle Pleistocene), Nanmenguan (Late Middle Pleistocene), Gongga (Late Pleistocene) ice ages, and the Pre-Guanjingtai Glacier Advance (\{>(3 080\}±80) a BP), the Guanjingtai Glacier Advance (\{1 530\}±80～\{2 350\}±65 a BP) and the Hailuogou Glacier Advance ((940±850)～(780±90) a BP), as well as the Little Ice Age (400～100 a BP). When the Yajiagen Glaciation, the ancient glacier type was piedmont one. During the Penultimate Glaciation (Nanmenguan one) the ancient Yanzigou Glacier extended into the Moxi Valley, at about \{1 550\} m a.s.l., and a glacier-dammed lake formed. When the glaciers retreated, some glaciofluvial lakes and glacier debris flows appeared on the Moxi Platform and along its lateral canals, where there are many big boulders, 10～20 m in diameter. During the last interglacial, when climate was warm and wet, red soil developed under the moraine, lacustrine deposit and deposit of glacier debris flow. During the last glaciation (Gongga Glaciation), the ancient Yanzigou Glacier was 22.4 km in length and extended to \{2 400\} m a.s.l. while the ancient Hailuogou Glacier was about 23 km long, with its terminus at 1 900 m a.s.l. Since the last glaciation four river terraces have formed. The relationship is very close between the glacier variation and the develop

关 键 词：第四纪 冰川作用 磨西台地 成因 贡嘎山 冰水沉积 更新世 冰川遗迹 

分 类 号：P544.1[天文地球—构造地质学] P343.6[天文地球—地质学]