Heavy mineral and detrital zircon U-Pb age analysis reveals a dominantly Yangtze River provenance for the East China Sea

The East China Sea is the largest offshore basin in southeastern China and a primary sink for sediments shed from the mainland. Despite its significance as a depocenter, the provenance of Cenozoic sandstones in the basin is poorly understood, as is their relationship to the evolving landscape of East Asia. Here, we pair newly acquired heavy mineral data from 8 samples from the East China Sea with new (N=4, n=286) and published detrital zircon U-Pb ages to evaluate provenance and likely modes of sediment transport from the East Asia mainland to the East China Sea since the late Eocene. Heavy mineral assemblages indicate that Eocene through Miocene sandstones of the East China Sea are similar and dominated by garnet, pyrite, zircon, and leucoxene, but also contain minor amounts of mica, hematite, limonite, and barite. Paleogene sandstones of the South Yellow Sea Basin, likely sourced from the North China Block, are also similar and dominated by ilmenite, garnet, and zircon. Modern sands from Oujiang and Minjiang rivers, a proxy for the provenance of east Cathaysia Block, however, differ, with amphibole, magnetite, mica, ilmenite, and epidote as the dominant heavy minerals. In addition to differences in heavy mineral assemblages, detrital zircon U-Pb ages also provide important clues to the provenance. Age spectra of the East China Sea samples are nearly identical to those of sands from the modern Yangtze River and its estuary, with pronounced 100300 Ma and 1,6002,200 Ma age clusters, and small early-middle Paleozoic, Neoproterozoic, and Paleoproterozoic-Archean peaks. Age spectra for the North China Block rivers are also similar to the East China Sea samples, with a prominent 350-250 Ma peak; however, ages <250 Ma are notably missing. In contrast, age spectra from the east Cathaysia Block rivers bear little resemblance to the East China Sea samples. Together, the datasets point to a river similar to the modern Yangtze River as the primary source of sediments to the East China Sea. However, the North China Block provenance in samples suggest that ocean currents, restricted to the Yellow Sea and East China Sea, may have played a role in mixing of sediments from different continental river systems.