Grain size analysis of the terrigenous fraction of sediments from IODP Site U1501 was used to characterize depositional patterns in the northern South China Sea since the Middle Eocene (∼35 Ma). Fine sand dominates the lower sequence (∼457–440 m CSF-A (core depth below sea floor – A)), reflecting turbidite influence on the Chinese continental shelf (∼35–34 Ma). This is followed by a fining-upward trend (4–8 phi) marking the transition to hemipelagic deposition mostly devoid of turbidites. A new silt-dominated sedimentation regime became established at ∼30 Ma, which correlates with the initial expansion of the Pearl River. The regime is accompanied by stable source geochemical proxies (e.g. Zr/TiO2 values) and remains unaffected by an unconformity (T60) and hiatus at ∼26.8–24.36 Ma. Grain size changes with stable geochemical proxies require variable intensities of terrigenous influx, which we propose reflect the dynamics of surface buoyant plumes and their controlling factors. At ∼16 Ma, sediment fines abruptly (4.7–7.5 phi) and grain size remains constant to the present, reflecting drier conditions in the source area that began shortly afterward. The observed patterns suggest that grain size data from hemipelagic sediments devoid of turbidites can be combined with source tracers to help reconstruct the intensity of buoyant plumes over time.