The development of fluvial systems in East Asia is closely linked to the evolving topography following India–Eurasia collision. Despite this, the age of the Yangtze River system has been strongly debated, with estimates ranging from 40 to 45 Ma, to a more recent initiation around 2 Ma. Here, we present 40Ar/39Ar ages from basalts interbedded with fluvial sediments from the lower reaches of the Yangtze together with detrital zircon U–Pb ages from sand grains within these sediments. We show that a river containing sediments indistinguishable from the modern river was established before ∼23 Ma. We argue that the connection through the Three Gorges must postdate 36.5 Ma because of evaporite and lacustrine sedimentation in the Jianghan Basin before that time. We propose that the present Yangtze River system formed in response to regional extension throughout eastern China, synchronous with the start of strike–slip tectonism and surface uplift in eastern Tibet and fed by strengthened rains caused by the newly intensified summer monsoon.

https://www.pnas.org/content/pnas/early/2013/04/17/1216241110.full.pdf

Pre-Miocene birth of the Yangtze River.

Linking slab break-off, Hellenic trench retreat, and uplift of the Central and Eastern Anatolian plateaus

Abstract We present a review and synthesis of the tectonic geomorphology along the eastern margin of the Tibetan Plateau adjacent to and north of the Sichuan Basin. Re-evaluation of spatial variations in the form of fluvial longitudinal profiles provides a refined image of the distribution of anomalously steep channels. Three new analyses demonstrate that these variations in channel steepness reflect variations in the locus and rate of differential rock uplift. First, measurements of channel width along trunk streams reveal systematic co-variations in channel hydraulic geometry and slope that suggests channels are dynamically adjusted to spatial variations in erosion rate. Second, recent determinations of the functional relationship between channel steepness indices and erosion rate allow a quantitative estimation of erosion rate from channel profile form. Third, comparison of rock uplift patterns to variations in the distribution of slip associated with the 2008 Wenchuan earthquake confirms that channel gradients reflect differential rock uplift. Our analysis suggests that reactivated fault systems adjacent to the Sichuan Basin are primarily responsible for accommodating differential rock uplift, but that rock uplift northward along the margin is not associated with active faults and is likely sustained by flow and thickening in the deep crust.

Tectonic geomorphology along the eastern margin of Tibet: insights into the pattern and processes of active deformation adjacent to the Sichuan Basin

Using advanced InSAR time series techniques to monitor landslide movements in Badong of the Three Gorges region, China

Spatial variation in Meso-Cenozoic exhumation history of the Longmen Shan thrust belt (eastern Tibetan Plateau) and the adjacent western Sichuan basin: Constraints from fission track thermochronology

Like the other large river systems that drain the area of the India-Asia collision, the Yangtze River was assembled through a series of Cenozoic capture events. These events are important for orogenic erosion and sediment delivery, but their timing remains largely unknown. Here we identify enhanced cooling in the Three Gorges region in central China, a key capture site during basin development, beginning at 40–45 Ma. This event is not visible in regional thermochronological data, but is near-contemporaneous with the onset of widespread denudation in the Sichuan Basin, just upstream of the Three Gorges. While we cannot rule out alternative explanations, the simplest mechanism that links these events is progressive capture of the middle Yangtze River by the lower Yangtze and the onset of incision in the Three Gorges. This model agrees with independent mid-Cenozoic estimates for the timing of middle Yangtze River diversion and capture, and provides a plausible outlet for large volumes of erosional detritus from the Sichuan Basin.

/pdf/did-incision-of-the-three-gorges-begin-in-the-eocene-329u0rqdl8.pdf

Did incision of the Three Gorges begin in the Eocene

We are grateful to [Zheng et al. (2011)][1] for their interest in our work, and welcome the opportunity to explore some of the issues surrounding the origin of the Three Gorges in more detail. Zheng et al. raise three primary concerns with our interpretation that incision of the Three Gorges likely

/pdf/did-incision-of-the-three-gorges-begin-in-the-eocene-reply-4guyhuiv6l.pdf

M. Wipf

Papers

Did incision of the Three Gorges begin in the Eocene

Did incision of the Three Gorges begin in the Eocene? REPLY