The linking of the upper-middle and lower reaches of the Yellow River as a result of fluvial entrenchment

Zhenbo Hu, Bao Tian Pan, David Bridgland, Jef Vandenberghe, Lian Yong Guo, Yun Long Fan, Rob Westaway

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Abstract

The upper–middle Yellow River flows through the Fenwei graben, a structure resulting from extensional tectonism that was formed and repeatedly extended during the Cenozoic. The drainage system within this graben was formerly isolated from the lower reaches of the Yellow River system by the Xiaoshan mountains, an actively growing ∼ NW–SE trending range. The modern course of the Yellow River takes it through this range along the Sanmen gorge, the formation of which was of great significance in that it initiated through-going drainage between the upper–middle and lower reaches of the system. The timing of this event, which was clearly a critical point in the evolution of the Yellow River, can be established by dating the terraces in the gorge. Intermittent deepening of this gorge by the Yellow River from a high-level planation surface capping the mountain range has resulted in the formation of five terraces. Magnetostratigraphic records from aeolian deposits accumulated on these surfaces provide a geochronological sequence for this geomorphic archive, in which the ages of the planation surface and of terraces T5, T4, T3, T2, and T1 have been determined as ∼3.63 Ma, ∼1.24 Ma, ∼0.86 Ma, ∼0.62 Ma, ∼129 ka, and ∼12 ka, respectively. Under the constraint of this chronological framework, a model for landscape evolution is proposed here. Uplift of the inner Fenwei graben and of the surrounding mountain ranges led to dissection of the 3.63 Ma old planation surface in conjunction with the formation of the Sanmen gorge. Drainage of the lake previously occupying the basin would have promoted incision into the fluvio-lacustrine graben sediments; indeed, gorge formation through the Xiaoshan may have been initiated or intensified by lake overflow. The ages obtained for the planation surface and uppermost terrace suggest that the formation of the Sanmen gorge and the initiation of the through-going eastward drainage of the Yellow River occurred between 3.63 and 1.24 Ma. Before the start of gorge entrenchment, the products of erosion in the modern upper catchment of the Yellow River were unable to reach the sea. The dramatic increase in deposition rates in the Bohai Gulf (at the mouth of the modern Yellow River in the East China Sea), ∼1.0 Ma ago, thus resulted from the initiation of an integral (enlarged) Yellow River catchment drainage through the Sanmen gorge; it does not imply an increase in erosion rates at that time.

Original languageEnglish
Pages (from-to)324-338
Number of pages15
JournalQuaternary Science Reviews
Volume166
Early online date11 Mar 2017
DOIs
Publication statusPublished - 15 Jun 2017

Funding

We are grateful to Xiaopeng Liu, Jian Zhang, and Prof. Qingyu Guan for assistance with the field sampling and laboratory analyses. The comments by Prof. Frank J. Pazzaglia, an anonymous referee, and the special issue editor, Stéphane Cordier, have led to considerable improvements and are gratefully acknowledged. This research is financially supported by the National Natural Science Foundation of China (Grant no. 41401001, 41571003), the Key Project of the Major Research Plan of the NSFC (Grant no. 91125008), the National Basic Research Program of China (2011CB403301).

FundersFunder number
National Natural Science Foundation of China91125008, 41401001, 41571003
National Key Research and Development Program of China2011CB403301

    Keywords

    • Fenwei graben
    • Fluvial incision rate
    • Planation surface
    • Sanmen gorge
    • Terrace
    • Yellow River

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