滇西北大理冰期及冰后期地壳变形速率

作者对区内大理冰期出露的几个剖面进行了详细观察、研究,对冰碛层中的泥炭夹层进行了~(14)C测定,其年龄为0.018～0.02Ma。 各国学者己注意到同一纬度的不同地区,冰川开始时间不同;同一时代的冰川其雪线高度也有所不同。就本区而言,大理冰期之冰斗,现今分布在不同海拔高度,高差千米以上。作者认为是大理冰后期的新造陆运动——后造山期的地壳运动所产生的断块活动的结果。 通过构造地貌学、第四纪地层学及年代学方法对区内主要活动断层及水系、分水岭等位错进行了研究,大理冰后期、全新世以宋地壳变形强烈,其垂直速率为40～50mm/a,水平速率为200～250mm/a,水平速率约为垂直速率的5倍。

DALI GLACIAL PERIOD IN THE NORTHWEST YUNNAN AND RATE OF CRUSTAL DEFORMATION IN POST~GLACIAL PERIOD

The study area is situated at 99?100?40'E, 25?0'-28, in Yunnan Province in southwest China. It is adjacent to the southeast border of the Himalayas \vhich is formed by the collison between Indian and Eurasian plates. The Dali glacial period was named in Diancangshan mountain of Dali county, Wnnan Province. It was named first ly by II.V.Wissmann in 1937. And itwas studied by professor Li Siguang and was considered as the last glacial epoch of Quaternary in China. The author has recently surveyed and studied several emergent sections of Dali glacial in the area, and dated peat bed to be intercalated, at 0.018 -O.C2 Ma D.P. Scholars from all over the country have noted that the begining time of different glacier of different area in a same latitude is different, and the height of snow line was also variable in a same glacial stage. It was mainly effected by theclimate, precipitation and so on, in the whole region, but tne effect of crustal movement in post-glacial period should not be negleced. The fossil cirques which was formed at the same height a.s.1., in former times are distributed at different height a.s.l. at present. The height difference may amount to more than 1000m. This is considered as a result of faultblock activities due to crustal movement in a new epeirogenetic movement in Dali post-glacial period. Result shows that in the post-glacial period, the crustal deformation in Dali is intense with the vertical rate of 40-50mm/a and the horizontal rate of 200 - 250mm/a.