The zircon story of the Pearl River (China) from Cretaceous to present

The modern Pearl River originates from SE Tibet and debouches into the South China Sea. The development of the Pearl River is closely related to the evolving topography following the tectonic evolution of the southern China continental margin and uplift of Tibet caused by the India-Eurasia collision. How topographic changes affected the development of the Pearl River, however, is still unclear. Here we use original and literature data on detrital zircon ages from both modem Pearl River sands and ancient strata drilled in offshore basins to reconstruct the evolution of the paleo-Pearl River catchment through time. Six phases are identified: 1) Early Cretaceous: the paleo-Pacific plate was subducting beneath the South China block and topography in South China was tilted to the west. The paleo-Dong River began to develop with limited length. 2) Late Cretaceous: back-arc extension in the South China Sea contributed further to the west-tilted topography. The paleo-Bei River started to develop and the paleo-Dong River continued to expand across southeasternmost China. 3) Paleocene to Eocene: active rifting in the South China Sea induced a major topographic change. The paleo-Dong and paleo-Bei joined, forming the paleo-Lower Xi River. 4) Early Oligocene: active uplift of Tibet and onset of sea-floor spreading in the South China Sea led to subsidence in the Cathaysia block. The paleo-Dong, paleo-Bei, and paleo-Lower Xi rivers remained limited to eastern Cathaysia. 5) Late Oligocene: accelerated uplift of eastern Tibet and post-rift subsidence of the northern South China Sea margin induced a radical change in the landscape of southern China, and transition from west-tilting to east-tilting topography. The paleo-Pearl River started to incorporate also its present western branches. 6) Early to middle Miocene: the east-tilting topography was enhanced during rapid uplift of Tibet and progressive closure of the proto-South China Sea, while the Pearl River evolved to its present configuration.