Field investigation revealed a series of acidic dyke swarm distributed in the Jieerkuduke area to the south of Ertix fault belt in the Southern Altay Range.The acidic dykes intruded in the Carboniferous volcanic-sedimentary rock sequence and the rocks of the dyke are rhyolite-porphyries.LA-ICP-MS zircon U-Pb dating indicates that the acidic dykes were formed at(279±3) Ma.Since dyke is the significant symbol of lithospheric(or crustal) extension,this dating provides important evidence for the Early Permian lithospheric extension in the Southern Altay Range.