Palaeogeomorphic reconstruction of the South China Sea: coupling tectonics, climate, and ocean dynamics

Throughout its extensive history, Earth’s surface has undergone dramatic transformations, accompanied by significant changes in climate, environment, and resources. Paleogeomorphology is the result of the interaction between deep Earth tectonic processes and surface processes. The coupling process between active tectonics and geomorphological evolution such as earthquakes, volcanic activities, glacial and fluvial processes represents a key interface. Research on paleogeomorphology is closely related to the interactions between the deep and shallow layers of Earth’s interior and is a crucial component of multi-layered, multi-scale Earth system science. Therefore, the reconstruction of global paleogeography and paleogeomorphology during geological time has long been a focus of interest among geologists. The South China Sea, as a sensitive region to global climate and oceanic environmental changes, has experienced significant changes in its topography and geomorphology due to its complex geological structure and dynamic hydrological processes. This region has become a key subject of Earth system science research. The evolution of its three-dimensional geological environment is deeply influenced by tectonic activity, climatic fluctuations, and ocean dynamics, making its changes highly complex and uncertain, which traditional methods fail to resolve accurately. Therefore, it is essential to approach the reconstruction of the paleogeomorphological evolution of this multi-phase tectonic region from a quantitative perspective. In recent years, with the accumulation of Earth system data and the application of machine learning methods in complex system modeling, machine learning-based Earth system simulation has gradually emerged as a new frontier method, particularly in paleoelevation reconstruction. The application of this technology significantly enhances the precision and predictive capabilities of simulations for geological evolution and environmental changes in the South China Sea region. However, using Sr/Ca and Mg/Ca ratios in paleoelevation reconstruction has certain limitations, primarily due to interference from factors such as geological background and climate change, with weaker environmental responses in extreme environments such as arid or cold regions. To improve the accuracy of paleoelevation reconstructions, multiple geochemical indicators (such as δ¹⁸O, δD, and Δ₄₇) can be combined, and experimental calibration can be applied to separate the effects of climate and elevation, thereby optimizing existing models. By combining three-dimensional evolution models, it is possible to reconstruct the geomorphological evolution of the region, explore the tectonic factors of the South China Sea's opening and closure, the arc-continent collision that led to the Taiwan orogeny, and the impacts of surface factors such as paleoclimate and sea-level fluctuations on the northern South China Sea's hydrological systems, topography, and basin sedimentation. This further reveals the intrinsic mechanisms between the complex geological evolution of the South China Sea and oceanic dynamical processes.