A Critical Appraisal of the Sensitivity of Detrital Zircon U-Pb Provenance Data to Constrain Drainage Network Evolution in Southeast Tibet

Provenance tools, particularly detrital zircon U-Pb analysis, have been widely employed to test drainage network evolution in southeast Tibet and its linkage with the growth of the Tibetan Plateau. Numerous provenance studies have been conducted on the sediments in the paleo-Yangtze and paleo-Red River drainage basins. Nevertheless, it is still hotly debated as to whether a "Mississippi" (dendritic) pattern Greater paleo-Red River, originating from southeast Tibet and draining to the South China Sea, existed in the early Cenozoic, and was subsequently captured by the paleo-lower Yangtze due to uplift of southeastern Tibet. In this study, in addition to presenting new data from the Gonjo and Jianchuan basins along which the Greater paleo-Red River is proposed to have flowed, we compiled all the published detrital zircon U-Pb data from the paleo-upper Yangtze and paleo-Red River drainage basins from Triassic and younger rocks. Our large database of detrital zircon U-Pb analyses shows that the different terranes in the paleo-upper Yangtze and paleo-Red River drainage basins have similar zircon U-Pb signatures since the Late Triassic closure of the Paleo-Tethys Ocean. Therefore, most of the sediments in the Cenozoic sedimentary basins in southeast Tibet could have been either deposited by long-distance transport in large rivers from southeast Tibet or recycled from local bedrock. Given the potential importance of sedimentary recycling that we have demonstrated, this poses challenges to the use of detrital zircon U-Pb analyses to determine paleodrainage in this region. We therefore further explored the previously relatively limited use of Sr-Nd isotopes on mudstones and detrital mica 40Ar/39Ar ages, with new analyses from the Gonjo and Jianchuan Basins, to determine if these techniques were better suited to reconstruct paleodrainage evolution. Whilst these techniques do show some promise, more analyses and strategic sampling are required to obtain a full understanding of the extent of their potential utility. Overall, our integrated provenance study indicates that the available data are not sufficiently conclusive to support or refute the Greater paleo-Red River capture model. In the southeast margin of the Tibetan Plateau, five large-scale rivers (Yangtze, Mekong, Salween, Irrawaddy, and Yarlung-Brahmaputra) flow through central Tibet to southeast Asia. How these rivers evolved during the Cenozoic uplift of the Tibetan Plateau remains a controversial issue. It has been hypothesized that, in the early Cenozoic, all the upper reaches of the five rivers flowed to the south and connected to the Red River flowing to the South China Sea, forming a "Mississippi" pattern Greater paleo-Red River; this Greater paleo-Red River was later captured by the lower Yangtze due to uplift of the Tibetan Plateau. Here we test the Greater paleo-Red River model by adding new data from Cenozoic sedimentary basins and providing a comprehensive compilation of available detrital zircon U-Pb data from different terranes of southeast Tibet. With this large data set, we found that the source signatures for the various terranes from southeast Tibet are indistinguishable due to zircon recycling. Moreover, we explored the use of Sr-Nd isotopes and detrital mica 40Ar/39Ar ages as potential alternative provenance tools to test the river capture model. The overall provenance data are insufficient to test the validity of the Greater paleo-Red River capture model. Detrital zircon U-Pb source signatures for various terranes of southeastern Tibet are indistinguishable Sedimentary recycling limits the utility of detrital zircon U-Pb approach to determine the palaeodrainage evolution of southeastern Tibet Sr-Nd isotopes and mica 40Ar/39Ar ages may be potential alternative provenance tools for paleodrainage reconstruction