Early Cenozoic drainage evolution in the Jianghan Basin: Constraints from detrital zircon U-Pb ages of surface rivers and cores in the basin

Abstract

Objective The evolution of large rivers is closely linked to the interactions between tectonic and climatic processes. Understanding the evolutionary history of these rivers is crucial for uncovering the influence of deep dynamic processes on the Earth's surface. In the Jianghan Basin, the preserved Cenozoic strata provide valuable insights into the evolutionary history of the Han and Yangtze Rivers. Methods By conducting a systematic analysis of detrital zircon U-Pb ages (n=690) in the Hanjiang River Basin, the sediments in the lower reaches of the Hanjiang River contain a mixture of fluvial detrital signals from the Qinling and Dabie mountains. The detrital zircon U-Pb ages of these samples from the lower reaches of the Hanjiang River are more representative for determining their provenance. We have compared these new data with previously published fluvial sedimentary zircon U-Pb ages from the Jianghan Basin, as well as detrital zircon U-Pb ages from drilling cores obtained from Early Eocene strata in the basin. Results Provenance analysis reveals that the detrital material in the Jianghan Basin during the Early Eocene was primarily derived from the Qinling-Dabie Mountains. This can be attributed to the significant difference in elevation between the depression within the Jianghan Basin and the surrounding uplifted orogenic belts, which provided the necessary conditions for the development of large rivers. It is important to note that the Wuling Mountain and Huangling Anticline rivers did not serve as the main sources of sediment supply for the central, eastern, and southern depressions of the Jianghan Basin during this time period. Additionally, the Yangtze River, located west of the Huangling Anticline, did not flow into the Jianghan Basin in the Early Eocene. Conclusion Overall, the sediments in the Jianghan Basin were predominantly proximal deposits sourced from the adjacent orogenic belt, which can be attributed to the exhumation of the orogenic belt and a monsoon-like climate in the early Cenozoic era.

Keywords

• jianghan basin
• zircon
• u-pb ages
• river evolution