甘肃的第三系全为陆相湖盆及山间凹地型沉积,其分布和发育状况完全受当时沉积环境的控制。许多湖盆及凹地的分布位置和范围与白垩纪相似,表现了某些继承性。较大型的沉积盆地主要分布于祁连山北麓及甘肃东部,而在北山、祁连山、秦岭西部三个地区则沿断陷分布着一些规模不等的山间凹地(图1)。 The Tertiary in Gansu is entirely continental and basin-shaped sediments, and its distribution and development are completely controlled by the depositional environment at that time. The location and extent of many lake basins and valleys are similar to the Cretaceous and show some inheritance. The larger sedimentary basins are mainly distributed in the northern foothills of Qilian Mountains and eastern Gansu Province. In the three areas of Beishan, Qilian Mountains and western Qinling, there are some mountain valleys with different scales distributed along fault depressions (Fig. 1).