Detrital zircon ages reveal Yangtze provenance since the early Oligocene in the East China Sea Shelf Basin

Abstract

The origin and evolution of the Yangtze River drainage system play a crucial role in the palaeogeographic and palaeoenvironmental evolution of East Asia. The source-to-sink history of this major Chinese river provides information on the initiation of a topographic gradient in East Asia driven by far-field and near-field effects of plate tectonics and elucidates the subsidence and depositional history of the depocenter in the East China Sea Shelf Basin (ECSSB). Unraveling age constraints on Yangtze provenance, however, remains a big challenge. Here, we review U[sbnd]Pb ages of detrital zircon grains from the Oligocene-Miocene successions of the north ECSSB and perform several statistical tests to quantify mixing proportions of different potential source areas that reveal similar age patterns as the modern Yangtze River. We conclude that the initiation of a modern-type Yangtze drainage was established before ~34 Ma, and confirm that in the Oligocene an eastward drainage system was in place from the Yangtze Craton to the ECSSB where huge depositional systems developed on the Chinese continental margin. Monte Carlo models imply that the Oligocene and Miocene sediments of the north ECSSB were mainly supplied by the Yangtze River and the North China Craton - South Korean rivers, and that during the Miocene (< 23 Ma) the Yangtze drainage system extended further southward, reaching the marginal basins of modern Taiwan.