滇西北老君山地区岩浆活动与 长江第一弯形成的关系

在野外观察的基础上，对长江第一弯的形成提出了新认识，首次研究了始新世岩浆活动与长江第一弯形成的关系。提出长江第一弯为始新世滇西北老君山地区（金沙江古河道）强烈的岩浆活动阻塞了古金沙江，导致其上游形成堰塞湖，并在玉龙雪山和哈巴雪山之间决口，在高原隆升的同时河道快速下切，形成虎跳峡，是河水改道东流的结果；计算了处于青藏高原东端研究区的隆升的幅度，对玉龙雪山而言，始新世至更新世，隆升幅度为3300m，加上更新世以来的隆升高度700m，累计隆升高度为4000m左右。

Relationship between the Formation of the First Bent of Changjiang River and the Magmatic Activity in Laojunshan District

Based on field observations, the author proposes a new understanding on the formation of theFirst Bent of the Changjiang River. It is the first time to study the relationship between the formation of theFirst Bent of the Changjiang River and Eocene magmatic activity, suggesting that the First Bent of theChangjiang River is the result from choking of the strong magma activity in Eocene. As a result, theupstream of the river became a natural reservoir, with channel bursting into breach between Mt. Yulong andMt. Haba, making Jinshajiang River run eastward. At the same time, the plateau uplift and the drasticdissection of river channel led to the formation of the Tiger Leaping Gorge. Taking Mt. Yulong as a base,the magnitude of uplifting in the study area (located in the eastern of the Tibetan Plateau) is calculated, withthe magnitude being 3300 m from Eocene to Pliocene, adding 700 m since Pleistocene, totaling 4000 m orso.