Quantifying the relative provenance contributions to submarine channel systems in the Qiongdongnan Basin since the Miocene: Implications for tectonic responses and channel migration

Abstract

The submarine Miocene Central Canyon and Pleistocene channel systems in the Qiongdongnan Basin constitute valuable sedimentary records that provide insight into the depositional processes and sediment routing from the hinterland to the deep sea. However, the primary source of sediment for the Pleistocene channel systems and the variation in relative sediment contributions since the Miocene from potential source terranes remain unknown. We have integrated new and published detrital zircon U–Pb ages and rare earth elements (REEs) from Pleistocene channel sands and late Miocene Central Canyon sands in the Qiongdongnan Basin to analyse the sediment routing system of these channel systems since the Miocene. Qualitative analyses of REEs, comparisons of detrital zircon age spectra, and multidimensional scaling plots suggest that the Red River is a significant source of sediment supply. The quantitative analysis of sediment mixing models indicates that the Pleistocene channel sands were mainly sourced from the Red River (62.8%–85.7%), followed by Central Vietnam rivers (4.8%–27.1%), with a minor amount derived from rivers in Hainan Island, Northern Vietnam and Southern Vietnam. Sand sediments, mainly from the Red River system, were deposited in the Yinggehai Basin, then transported and deposited again in the Qiongdongnan Basin. The relatively stable and major sediment supply from the Red River since the Miocene may have been driven by the uplift of the Tibetan Plateau. This study quantifies the relative provenance contributions to submarine channel systems in the Qiongdongnan Basin since the Miocene. It provides crucial geological implications for tectonic responses to channel migrations and the prediction of gas hydrates in sandy reservoirs.