Luminescence dating reveals late Quaternary evolution of the Pearl River Delta estuary (China) in response to global climate and sea-level changes

The dynamic interaction at the interface between the alluvial river networks of the Pearl River Delta (PRD) plain and the northern continental shelf of the South China Sea has spurred the development of world-class port clusters, advanced manufacturing belts, and innovation-led urban agglomerations. Investigating the sedimentary evolution of large river deltas holds crucial significance for deciphering regional geological processes, paleoenvironmental changes, sea-level fluctuations, and human-natural interactions, offering insights into coastal system resilience and sustainable management in the context of global climate change. However, the chronological framework of the late Quaternary depositional stratigraphy in this region and the formation timing of the initial marine transgression events have not yet been conclusively established. Here, we reconstruct the late Quaternary sedimentary history of the present PRD estuary based on sedimentological investigations and multi-method dating of a 53-m-long drill core (CP-QZ04). Sedimentological analyses encompass lithological features, photographic documentation, and grain size variations of core sediments. The chronology of this study borehole was established by combining quartz optically stimulated luminescence (OSL) dating, polymineral grains (4–11 μm) and single-grain/multi-grain K-feldspar post-infrared infrared (pIRIR₂₂₅) dating, and radiocarbon (¹⁴C) ages. Collectively, we established the first reliable chronology covering approximately 311 ka for the PRD stratigraphy in its present estuary region, which has never been reported in previous studies. Stratigraphic analysis indicates that the Late Quaternary depositional sequence within the present PRD estuary records distinct paleoenvironmental stages. Pre-Marine Isotope Stage (MIS) 9 deposition was dominated by alluvial conglomerates that underwent intense weathering. This was succeeded by a fluvial-dominated terrestrial depositional regime that persisted from MIS 9 to MIS 7 (ca. 311–196 ka). During the MIS 6/5 transition (196–132 ka), the sedimentary facies shifted to coastal plain deposits, reflecting alternation of marine regression and transgression associated with sea-level fluctuations. The Holocene sequence (<11.7 ka) exhibits a characteristic vertical succession from intertidal mudflat to prodelta facies, indicating progressive marine inundation. Notably, this study identifies two major depositional hiatuses within the sequence: the first corresponding to MIS 5 (130–71 ka) and the second spanning MIS 4 to MIS 2, extending into early Holocene (71–9 ka). These stratigraphic discontinuities, marked by abrupt lithological contacts and paleosol development, likely reflect eustatic sea-level fluctuations, subaerial exposure, surface erosion and/or depocenter migration. In contrast, those terrestrial-marine interactions in this core are primarily governed by glacial-interglacial cycles, characterized by enhanced terrestrial input during warm interglacial periods and intensified marine influence during sea-level highstands, although modulated by local sediment flux and tectonic settings. Regional correlations align the late Quaternary depositional patterns of the present PRD estuary with those of its inland plain and adjacent coastal records in southern China, highlighting the dominant control of global climatic and eustatic factors on coastal evolutionary processes. This study establishes a robust framework for understanding delta-estuary system responses to late Quaternary environmental changes, thereby projecting future coastal dynamics under climate-driven sea-level rise scenarios.