Limited Effect of the Pearl River on the Pearl River Mouth Basin Before the Early Miocene

Abstract

The Pearl River has received particular attention with respect to its links to the growth of the Tibetan Plateau and associated landscape evolution. However, controversy still surrounds the issues of when the present-day Pearl River became established, and how landscape deformation may have triggered the formation of the Pearl River. In this study, new and published zircon U–Pb ages from the late Oligocene Pearl River Mouth Basin (PRMB) and potential source areas are used to conduct a systematic provenance analysis with a view to reconstructing the drainage pattern in the South China Block. The results suggest that the PRMB was fed by multiple major sources during the late Oligocene, exhibiting significant spatial provenance variability. The paleo-Pearl River had a limited effect on the northern and southern PRMB during the late Oligocene, and there was an overlooked Yunkai Massif source which made a significant contribution to the western and southern PRMB. We infer that, compared to the early Miocene or the present day, a paleo-Nanduhe River with a larger catchment area flowed through the Yunkai Massif into the PRMB in the late Oligocene, and the paleo-Pearl River only drained the less extensive Cathaysia Block during this time. In the early Miocene, the westward expansion of the paleo-Pearl River and the capture of the upstream part of the paleo-Nanduhe River by the paleo-Pearl River, which are attributed to the growth of the Tibetan Plateau and the exhumation of the Yunkai Massif, respectively, resulted in the present-day Pearl River configuration with its dominant impact on the PRMB.