Cenozoic sequence stratigraphy and sedimentary evolution of forearc basin in Ryukyu Island Arc region

The Ryukyu forearc basin is located at the convergence of the northern Philippine Sea plate and the Eurasian plate. It is developed between the accretionary wedge in the northern Ryukyu trench and the Ryukyu Island Arc. It is a component unit of a typical trench-arc-basin' system. Now, based on the multi-channel seismic data, the sequence stratigraphic framework established for the first time in the study area is used to analyze the Cenozoic sequence stratigraphy and sedimentary evolution characteristics, and discuss the main source of sediment. According to the characteristics of seismic reflection and the contact relationship of reflection layer group, it is revealed that the Cenozoic in the study area experienced the process of shallow marine facies, semi-deep marine facies and deep-sea facies. It is considered that island arc metamorphic basement sedimentation developed in Eocene, and the basement sedimentation period of residual extensional basin from Late Eocene to Early Miocene belongs to the basement sedimentation period of fore arc basin, which is a shallow sea environment and mainly develops pyroclastic lithofacies; The Middle Miocene to Quaternary is the main sedimentary period of the forearc basin. It transited from the bathyal to the deep-sea sedimentary environment. The local volcanic elastic facies developed many typical sedimentary systems, such as gravity flow, turbidite fan, underwater delta and turbidite channel. It is inferred that the South Ryukyu Islands in the northern part of the Middle Miocene was the main provenance in the forearc basin period. Since the Late Miocene, the land area in the northeast of Taiwan Island has become the largest provenance, and the South Ryukyu Islands is in the second place. The results are an extension of the study on the basin control of the Ryukyu Island Arc and its surrounding structures, and have important guiding significance for the study of the source-sink' system of the land and eastern sea area of Taiwan Island.