一、引言本文所指的祁连山东南部,其地理范围是从西到东包括了甘肃的武威、古浪、天祝、永登,青海的亹源、大通、民和以及兰州以东地区,其地理方位约居东经101°20′—105°00′,北纬35°40′—38°00′(图1)。按地质学家习惯的命名,侏罗纪地层在兰州附近称为阿干 I. INTRODUCTION The southeastern Qilian Mountains referred to in this paper include the geographic ranges of Wuwei, Gulang, Tianzhu, Yongdeng, Qingyuan, Huangyuan, Datong and Minhe in Gansu and the areas east of Lanzhou from west to east The geographical location is about east longitude 101 ° 20’-105 ° 00 ’and latitude 35 ° 40’-38 ° 00’ (Figure 1). According to geologists accustomed to naming, Jurassic strata in Lanzhou near known as Agan