Zhong, Yuezhi , Willett, Sean D. , Picotti, Vincenzo , Xiong, Jianguo , Zhang, Huiping
2022-01-01 JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE 2022 127(卷), 1(期), (null页)
We present a model to reconstruct spatiotemporal variation of uplift along the Jinshan Gorge of the Yellow River of Northern China based on quantitative analysis of the river channel profiles. We focus on the tributaries along the gorge that drain from the Loess Plateau on the Ordos crustal block. Base level fall on a tributary is genetically related to its trunk channel incision through the incision rate of the confluence point. We leverage this relationship to reconstruct a scaled incision history at each confluence point from an inversion analysis of tributary networks governed by the stream power law. In this way, we create an artificial geomorphic marker, that we refer to as a "pseudo-terrace." These metrics provide information on the incision history of the Yellow River. Our result shows a recent acceleration of river incision along the southern Jinshan Gorge, including spatial variations indicative of tectonic activity. The northern gorge exhibits more uniform and steady incision rates. This pattern can be attributed to on-going lithospheric mantle upwelling beneath the southern Ordos Block. Plain Language Summary Deformed river terraces serve as a landscape feature to investigate tectonic activity, however, at timescales over about 10(5) yr, most markers, including river terraces, are destroyed by river erosion. The increasing fragmentation of preserved terraces through time can limit investigations on landscape deformation history. To recover the longer-term (similar to 10(6) yr) incision and uplift history, we incorporate the incision recorded by the river channel profiles and create a virtual metric, named as a "pseudo-terrace." We apply the method to analyze profiles of tributaries along the Jinshan Gorge in the middle reach of the Yellow River and get a high-resolution pattern both in space and in time. The pattern shows higher river incision rates in the southern Ordos Block. The variation is attributed to deep mantle flow associated with lithospheric extension. Besides the large-scale pattern, smaller offsets and tilts of pseudo-terraces are also illustrated, indicating surface or near-surface faulting or folding was active in the past 2 Ma.
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