【摘要】 <正> 一、前言四川省西昌邛海盆地为一第四纪构造盆地,呈北北西向的不规则长方形展布,长约15公里,宽约5—6公里,盆地的中、南部为邛海湖所占据。邛海是一面积约31平方公里的淡水湖,湖岸线长约35公里,最大水深达30余米。更多还原

【Abstract】 On the basis of the data from field investigations, the age and evolution ofthe Qionghai lake basin are discussed in this paper. The ?main conclusions are asfollows: 1. The Qionghai lake basin is a down-faulted basin formed during the Quater-nary. It took shape finally in the middle and late parts of the late Pleistocene. 2. The formation of this basin can be divided into two stages of development.In the first stage, from the early part of the early Pleistocene to the early partof the middle Pleistocene, the Qionghai graben was formed, which was a part of the NNW-trending graben-horst system. In the second stage, from the early tomiddle part of the late Pleistocene, the Qionghai graben was cut by a near-E-W-trending fault and changed into the Qionghai massif. This massif subsided underthe action of gravity; thus the presnt shape of the lake basin was formed. 3. The Qionghai lake basin is located a? a specific area where the boundaryfault zone at the eastern side of the Sichuan-Yunnan rhombic fault block turns.The origin of the basin is closely related to the movement of the boundary faultzone.更多还原