Precise zircon U- Pb ages that constrain the Lower Cambrian strata in the Tarim Craton are rare. Recently the authors identified a layer of 10~20 cm tuff interbedded at the bottom of the siliceous rocks of the Xishanbulake Formation in the northern Kuruktag area, located in the Tarim Craton. The LA- ICP- MS zircon U- Pb age of crystal tuffs yielded a depositional age of 520. 3±2. 9 Ma (MSWD=0. 11). The accurate〖JP〗 zircon U- Pb age data of the Lower Cambrian strata in the Tarim Craton are provided for the first time, and a prototype of the time frame based on the zircon U- Pb age is constructed. Using the deposition rate of the Lower Cambrian of the black rock series in South China, the sedimentation of the Xishanbulake Formation may have begun at 532. 1±2. 9 Ma in the Qieganbulakedaban section of northern Kuruktag. Combined with regional stratigraphic correlation, the Ediacara- Cambrian sedimentary discontinuity in the northern Kuruktag area at 50 Ma was affected by the western Mountain Movement.