Abstract: The age of the felsic tuff interbedded with the Luobusha conglomerates in western Zetang County is reported for the first time in this paper. LA-ICP-MS zircon U-Pb analysis shows that the tuffs were formed at 18.7±0.2Ma, and hence the time of the initial deposition should be about 20Ma, whereas the LA-ICP-MS zircon U-Pb age of granite underlying the Luobusa conglomerates is 29.9±0.4Ma. The existence of the tuff documents a volcanic activity developed at 18.7±0.2Ma. In combination with geochronologic data from previous work, the authors hold that volcanic activities were developed all along the Yarlung Zangbo suture zone, meaning the re-activation of the suture zone, which is remarkably similar to the potassic-ultrapotassic volcanism along the Gangdise zone in time and space.