Birth of the Yangtze River: age and tectonic-geomorphic implications

Abstract

AbstractLarge river systems are an integral and essential component of Earth dynamics. The development of large river systems in Asia is closely linked to the evolving topography driven by both near-field and far-field effects of the interplay among Indian, Eurasian and Pacific plates. Plate tectonics together with climatic changes during the Cenozoic is therefore believed to have determined the evolution of Asian large rivers, yet the age of the Yangtze, the largest in Asia, has been strongly debated over a century, with estimates ranging from 40–45 Ma to a more recent initiation postdating 750 ka. In this paper, I attempt to review the competing views about the age of the Yangtze, and evaluate the estimated pre-Miocene birth of the river based on the provenance of the fluvial sediments from the lower reaches. I further present new geological evidence from the upper stream in southeastern Tibetan Plateau to show the existence of a possible southward paleo-Jinshajiang during the Paleogene, and exploit when and how it might deviated eastward to give birth to the modern Yangtze River. I propose that the present Yangtze River system formed in response to the continental-scale gradient driven by uplifting Tibetan Plateau and regional extension throughout eastern China, synchronous with surface uplift in southeastern Tibet and strengthening of Asian summer monsoon.