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冰川冻土 ›› 1983, Vol. 5 ›› Issue (3): 171-178.

• 研究论文 • 上一篇    下一篇

天山博格达峰四工河5号冰川前缘的槽碛垄

郑本兴   

  1. 中国科学院兰州冰川冻土研究所
  • 出版日期:1984-11-25 发布日期:2012-04-26

Fluted Moraines Near the Terminus of Glacier No.5 of Sigong River in Mt. Bogda, Tian Shan

Zheng Benxing   

  1. Lanzhou Institute of Glaciology and Cryopedology, Academia Sinica
  • Online:1984-11-25 Published:2012-04-26

摘要: 槽碛垅是位于冰川前面低平处、与冰川流向一致的沟垅相间的平行冰碛垅。在国外对槽碛垅的报道和成因探讨的文献很多[1-3]。在国内有关槽碛垅的报道极少。1980年我们在天山乌鲁木齐河源1号冰川前注意到槽碛垅,其形态仅数十厘米高。1981年我们在博格达峰北坡四工河5号冰川前观测到的槽碛垅,数量多,高度大,可以说是我国到目前为止所发现的槽碛垅最发育的地区。本文就它们的形成特征、粒度组成、组构与其成因问题进行讨论。

Abstract: Fifty six rows of fluted moraine in the same direction of ice flows and in alternative ridges and gullies on a flat front 370 m wide at the terminus of Glacier No.5 on the northern slope of Mt. Bogda were surveyed in 1981. They are generally 10-40 m long, 1-3 m wide and 0.5-1 m high, the greatest being 110 m long, 12 m wide and 4 m high. Such a group of fluted moraine was recorded in China for the first time, and is moderate in scale as compared with those in North Europe and North America.The composition of grain size in the fluted moraine is similar to that in the end till and basal till,but its content of silt is relatively high, reaching 16.65% ,nearing 18.04% in the lower lodgement till,and higher than 7.7% and 3.6% in the upper lodgement in the eskers. The abrasion exponent in the fluted moraine is 0.63, close to 0.66 in the lower lodgement till, but larger than 0.44 in modern terminal moraine and 0.29 in esker, showing that both the fluted moraine and the lodgement till were rather strongly abrased by glaciers.The fabric of the fluted moraine shows the following characteristics. The dip of long axis A is in the same direction of glacial movement, but on the both sides the farther the down slope, the larger the angle between the dip and the direction of glacial movement, and the dip angle varies from about 10? near the top to 40-56? near the bottom. The dip of maximum AB plane is mostly perpendicular to the direction of ice flow, and the dip angle is rather big, about 2/5 of the gravels is more than 50?.There are big boulders at the head of some fluted moraines, and at the head of many moderate and small rows of the fluted moraines are ice anticlines rich in debris dipping upwards. From above mentioned, the formation of the fluted moraine could be inferred as follows: when the glaciers moved forward,the boulder in the lodgement till distributed unevenly,and hindered the movement of the ice, as a result, a low pressure area in the ice flow occurred in front of the obstacles and forced the lodgement till protrude upward in the form of ridges, and the ice layer folded.