The Cenozoic evolution of the Yellow River

Abstract

The evolution of rivers is closely tied to basin tectonics and climate change. Consequently, understanding the formation and evolution of large rivers (which can traverse diverse geological units and potentially complex climatic zones) can provide valuable insights into regional to continental tectonic activity and climate change. The Yellow River, which originates in the Tibetan Plateau and flows into the western Pacific Ocean, is the longest river in northern China, spanning approximately 5464 km. Previous research suggests that critical development stages of the Yellow River took place in a punctuated fashion during the Eocene, Miocene, and Pliocene to Pleistocene but the drivers have not been comprehensively investigated. In this study, we examined published UPb detrital zircon data from sedimentary basins and boreholes in the upper, middle, and lower reaches of the Yellow River (n = 15,976) to resolve the evolution of river segments, as well as the broader catchment. These data were then compared with UPb zircon data from potential source areas (n = 16,976), with consideration of the reported sedimentology, climate, and tectonic context of the region in order to create a more holistic model of the Yellow River system evolution. The results suggest that the Yellow River catchment developed within a large-scale foreland basin and fault basin, primarily influenced by the subduction of the Indian and Pacific plates towards the Asian continent during the Paleogene. Arid climate conditions during the Paleogene favored the development of an endorheic river system in the Yellow River catchment. During the middle Miocene, what is now considered the upper reaches of the Yellow River flowed from the northeastern Tibetan Plateau into the Yinchuan Basin, influenced by the expansion of the northeastern Tibetan Plateau. Nonetheless, the “proto-Yellow River” (temporal equivalent of the upper and middle reaches of the Yellow River) stayed on the rain-shadow side of the East Asian summer monsoon during this period, resulting in arid climates and the formation of endorheic rivers. What is now considered the lower reaches of the Yellow River, including the Kaifeng, Bohai Bay, and South Yellow Sea basins, developed independent depocenters that were not interconnected during the Miocene. The present-day upper, middle, and lower reaches of the Yellow River were not connected during the middle Miocene. During the Pliocene, the upper Yellow River originated in the Guide and Xining basins and flowed into the Yinchuan Basin. However, the arid climate and fault depression in the Hetao Basin impeded the current upper Yellow River from flowing into the Jinshan Canyon in the middle reaches. During the Pliocene, the temporal equivalent of the middle reaches of the precursor Yellow River had already extended into the Sanmenxia Basin, a state that is referred to here as the eo-Yellow River (the Yellow River began to develop in its middle reaches). During the early and middle Pleistocene, the exhumation of the Tibetan Plateau and the high-amplitude fluctuation of the East Asian summer monsoon drove the development of multiple levels of gravel-dominated fluvial terraces along the present-day upper and middle Yellow River, with increased sedimentation rates and thick sand layers along the lower Yellow River recording the river's strong hydrodynamic transport capability. In the early Pleistocene, the Yellow River achieved interconnection of its present-day upper, middle, and lower reaches. The Cenozoic evolution of the Yellow River catchment exemplifies the complex influence of tectonic activity and climate change on fluvial systems, and ultimately on the denudation of continents. This study advances our understanding of the interplay between Tibetan Plateau exhumation, river evolution, and monsoon climate in East Asia during the Cenozoic.