南海南部陆缘盆地裂陷-漂移-前陆期构造演化及沉积响应：以礼乐盆地为例
摘要
Based on the analysis of tectonics-stratigraphy-sedimentology in Liyue Basin, this paper finds out the characteristics of tectonic evolution and sedimentary fillings, reveals the genetic relationship between the basin evolution and the spreading of the South China Sea (SCS), and provides the reference for the study on the marginal sea evolution of the SCS.The Cenozoic tectonic-sedimentary evolution of the Liyue Basin could be divided into three distinct stages: the first stage characterized by continental marginal rifting and littoral-neritic clastic sedimentation from Paleocene to Early Oligocene, the second stage characterized by detaching-drifting and neritic carbonate sedimentation from Late Oligocene to Early Miocene, and the third stage featured with peripheral foreland flexure subsidence and regional differential sedimentation since Middle Miocene.In the first stage from Paleocene to Early Oligocene, the southeastward subduction of the Proto-South China Sea (PSCS) resulted in the passive rifting of the ancient South China Plate under the action of horizontal extension, and then the formation of the Liyue Rifting Basin.During this period dominated by the littoral-neritic depositional environment from Paleocene to Early Oligocene, controlled by detrital sediments supply and the PSCS action, a series of relatively large-scale braided river deltas developed in the northwestern basin, however, few small-scale fan deltas developed on the edge of the isolated uplifts in the eastern and southern basin adjacent to the PSCS.In the second stage from Late Oligocene to Early Miocene, accompanying with the PSCS continuous subduciton and the SCS initialization and spreading, the Liyue Basin located on the Liyue-Balawan Plate detached from the South China ancient continent, and then southwards drifted with slow subsidence and weak faulting.During this period dominated by the neritic- bathyal depositional environment from Late Oligocene-Early Miocene, due to the scarcely detr