The comparison of detrital zircon geochronology between mountainous rivers in Eastern China and its implications for marine sediment provenance

The detrital zircon geochronology is commonly applied to trace the sediment provenance, reconstruct the paleogeography, and reveal the tectono-sedimentary evolution history. Although zircon is an extremly tiny mineral (10^-5~10^-4m), it may provide geological information of such a large spatial scale (> 10¹⁰m²) as the India-Asia collision, the birth of the Yangtze River and the tecotono-sedimentary evolution of Taiwan Island. The aim of this study is to reveal the characteristics and controlling factors of the detrital zircon geochronology of mountainous rivers by comparing zircon U-Pb ages of river sands between two kinds of river basins drainning through different lithology (sedimentary rocks and igneous rocks) in southeastern China.In this contribution, we measured the detrital zircon U-Pb ages of the river sands from the Zhuoshui and Lanyang Rivers of Taiwan, and collected zircon age data of four small mountianous rivers in southeastern mainland from literatures. It is found that there is a huge discrepancy in the detrital zircon geochronology of small mountainous rivers in southeastern China. The zircon age populations of the Jiulong and Ou Rivers are very simple, with a dominant peak in late Mesozoic age. As the basin area becomes larger, the North and Min Rivers show more zircon age groups, including Mesozoic, Paleozoic and Precambrain peaks. In comparison, although the basin areas of Taiwanese mountainous rivers are extremly small ((1~3)×10³ km²), the zircon age distributions are very complex. Especially, the Zhuoshui River owns a high proportion of Precambrain zircons.In order to reveal the controlling factors of the detrital zircon geochronology, the zircon U-Pb age distributions of river sands in southeastern China are compared with the bedrock characteristics in related river basins. It shows that the detrital zircon geochronology of river sands in southeastern mainland corresponds well to regional tectono-igneous activities. By contrast, the detrital zircon geochronology of river sands in Taiwan is closely related to the tectono-sedimentary evolution of this lsland.In addition, based on the characteristics of the detrital zircon geochronology of river sands, the medium- and samll- sized mountainous rivers in southeastern China can be divided into three end-members. The first is the small rivers along the southeastern coast, which have an intense Yanshanian age peak. The second is the medium-sized rivers in southeastern mainland with an obvious Caledonian age peak. As to the third, the western rivers in Taiwan own not only a high proportion of Precambrain zircons, but also obvious Jinningian and Lüliangian age peaks. To sum up, characterizing these end-members can provide important instructions for tracing the provenance of coarse sediments deposited in the Taiwan Strait and the inner shelf of the East China Sea during the last glacial period.