Long-Distance Sediment Dispersal from Taiwan Recorded in South China Sea Proxy Records

Multi-proxy studies of the Kueichulin Fm of the Taiwan Western Foreland Basin show that the Taiwan orogen became a major source of sediment to the basin by ~5.4 Ma and began to overwhelm sediment contributions from Eurasia. Our study of late Miocene–early Pleistocene gamma-ray, δ13CORG, hematite/goethite, and magnetic susceptibility records from the Western Foreland Basin and SCS deep-sea proxy records show that sediment dispersal from the Taiwan orogen reached far into the South China Sea (SCS) since the early stages of its emergence from the Pacific Ocean.

Sedimentary archives from northern and central SCS show decreasing trends in hematite/goethite soon after ~5.4 Ma, reflecting the transport of large volumes of hematite-depleted sediment from Taiwan. By ~3.2 Ma, continued southwest migration and growth of the Taiwan orogen resulted in the formation of northward-flowing currents that transported some sediment from Taiwan towards the East China Sea, resulting in a relative decrease in sediment input from Taiwan to the SCS and increase in contributions from Eurasia and Luzon. In the southern SCS, the Mekong River has dominated sedimentation since the late Miocene, and thus proxy records show no influence from the Taiwan orogen.

Our study shows that a rapidly uplifting and eroding orogen can influence deep-sea sediment records located >1000 km away from the orogen. Our results also emphasize the need to consider the influence of shifting sediment sources on deep-sea proxies that are traditionally interpreted to reflect changing environmental conditions to confidently reconstruct past climate change from sedimentary records.