Abstract: The depositional sequences spanning about 0.3-3 Ma formed within the third-order cycles of eustatic changes in a marine basin are thought to be comparable on a global scale. The Zhujiang River mouth basin studied here is a marginal ex tensional basin in which a succession of vertically cy clic siliciclastic sediments laid dow n. The second member of the late Oligocene Zhuhai Formation may be further divided,on the basis of the three-dimensional high-resolution seismic section, drilling core and well logs data in integration with the recog nition of stratig raphic cy cles, accom modation spaces and key boundaries, into two third-order sequences:S₁ and S₂. These sequences are commonly lack in the low stand systems tract and locally filled with faultconfined submarine canyon sediments.