Holocene provenance evolution of the northern South China Sea inferred from detrital zircon U-Pb geochronology and Hf isotopes

The Holocene sedimentary evolution in the northern South China Sea has significant implications for sedimentary records resulting from combinations of climate change, sea level rise, and changes in surface circulation. U-Pb geochronology and Lu-Hf isotopes of detrital zircons from the Holocene sediments at the head of the Shenhu submarine canyons, integrated with onshore geochronological data reveal variations in provenance related to these factors. The detrital zircons exhibit a wide range of U-Pb ages from 3829.7 to 41.5 Ma characterized by peak ages centered on 140-154 Ma, 240-258 Ma, 425-452 Ma and 738-991 Ma. Zircon Hf isotopic compositions show a broad range of 176Hf/177Hf ratios from 0.2800714 to 0.282924, with & epsilon;Hf(t) values ranging from -27.8 to +14.3. Our results suggest that the Holocene sediments were primarily derived from the Pearl River system and the drainage systems in Taiwan, and the sources in Hainan and Luzon are not represented in these sediments. A rapid shift from Pearl River-dominated to Taiwan-dominated provenance occurred between 4.91 and 4.45 ka BP, which is interpreted to be caused by sea level rise and variations in the surface circulation in the northern South China Sea during the Holocene. Our study also reveals that the reworking of ancient continental crust dominated the evolution of the South China Craton, including tectonic-magmatic events at ca. 2491 Ma, 1843 Ma, 968 Ma, 810 Ma, 440 Ma, 251 Ma and 147 Ma. In contrast, Neoproterozoic accretion of the Cathaysia and Yangtze blocks was accompanied by juvenile additions to crustal growth.