Episodic sedimentary processes with significant changes in sedimentation rate have occurred on the East Hainan Coast, the inner shelf of the South China Sea, since the Last Glacial Maximum. In particular, the early-Holocene (~11.5–8.7 ka) rapid sedimentation at a mean rate of ~4.90 m/ka is crucial to understand the processes of terrigenous input to the ocean, carbon cycling and climate control in coastal-neritic sedimentary evolution. However, the chronological framework and the detailed environmental evolution remain uncertain. In this study, core sediments collected from the East Hainan Coast (code: NH01) were used to revisit the characteristics of luminescence signals by comparing the dating results using the blue-light stimulated luminescence (blue-OSL) ages and previously published post-infrared blue-light stimulated luminescence (pIR-blue OSL) ages. The results showed that both the ages agreed with each other for the fine-grained quartz fraction. The refined chronology of the early-Holocene deposits on the East Hainan Coast with higher resolution suggested that the sedimentation rate was ~0.60 m/ka before 10.97 ka, while it increased abruptly to ~5.89 m/ka during the period of 10.97–9.27 ka. According to the refined OSL chronology and the high-resolution (~2.5 cm) titanium intensity using X-ray fluorescence (XRF) scanning, the rapid sedimentation during the early Holocene was likely controlled by increased terrigenous input. The variation in Ti flux reflected the differential response between two meltwater pulse (MWP) events under the combined effects of enhanced early-Holocene monsoons and localized freshwater input. These findings highlight the compound controls of global ice-volume change, monsoon dynamics and coastal geomorphic evolution on sedimentary processes.

The area from Tonggu Cape to Qinglan Bay off eastern Hainan Island, China, is a bedrock headland coast with a river-mouth lagoon and hosts typical habitats such as coral reefs. Qinglan Bay is located on the path of sediment transportation along the north continent of the South China Sea, the crucial area of clastic sediment diffusion in the continent and Hainan Island; therefore, investigating the sedimentary dynamic environment in the nearshore area off Qinglan Bay is particularly important. Grain size analysis was performed on 321 seafloor sediment samples collected from the waters off Qinglan Bay. The seafloor sediments in the study area can be classified into eight types, dominated by muddy sand, silty sand, and sand. In this study, the Gao–Collins method was applied to the grain size data to perform grain size transport analysis. Combined with submarine topography, the headland effect of Tonggu Cape, the sheltering effect of coral reefs, and the combined transport and shaping effects of tidal currents, waves, the coastal current, and human activities, we infer the possible sediment source compositions of the northern and central-southern sedimentary environment zones. In the northern zone, eroded material from Tonggu Cape and open-sea sediments are mainly controlled by seabed characteristics composed of coral reefs and rocks during deposition. In the central-southern zone, coastal erosion material and open-sea sediments are mainly controlled by the mixing of terrestrial and open-sea sediments, driven primarily by currents, waves, and tidal currents. These findings improve the understanding of modern sedimentary processes in the study area and provide basic scientific data for coral reef conservation, coastal protection, and port and navigation support.