采用Rb-Sr法对阿拉善断块有代表性的苏亥图、温都尔浩富碱侵入岩体的年龄进行了测定 ,分别获得 (2 5 0± 18)Ma和 (2 13. 0± 9. 8)Ma的年龄值 ,提供了属于印支期的年代学证据 ,认为阿拉善断块北缘富碱侵入岩和华北断块北缘燕辽—阴山印支期富碱性侵入岩带应该划归同一印支期富碱性侵入岩带。推断阿拉善断块和华北断块在晚古生代—印支期可能处于同一地球动力学体系内 ,而塔里木断块可能处于另一地球动力学体系。 The Rb-Sr method was used to determine the age of the Huhentu and Wortoul-Alkali-intrusion rock masses representative of the Alzheitan fault block. The ages of (205 ± 18) Ma and (2.13 ± 9. 8) The age value of Ma provided chronological evidence belonging to the Indo-Chinese Epoch. It is considered that alkali-rich intrusive rocks in the northern margin of the Alxa Fault Block and Yanliao-Yinshan Indosinian alkali-rich intrusive rock belt in the northern margin of the North China Fault Block Should be assigned to the same Indosinian alkaline-rich intrusive rock belt. It is concluded that Alzheh fault block and Huabei fault block may be in the same geo-dynamical system during Late Paleozoic-Indosinian, whereas the Tarim block may be in another geodynamical system.