Abstract: During the Yanshanian movement, under the action of regional dextral shear stresses the NE-trending Banlingxia fault continued its dextral shear motion and the Sishun ring structure was derived in its southeastern wall. The ring structure was spurred to rotate sinistrally, forming an extensional region in the Tiemuli area, which created a favourable tectonic environment for the emplacement of the Tiemuli Rock Group. The extension occurred several times in the way of "pulsation". Each pulsatory extension was followed by a magmatic emplacement （or cryptoexplosion）, thus forming an east-west framework of cryptoexplosion breccia body→latite porphyrite body→syenite porphyry body→ibotite granite body.