Tectonic and Lithologic Controls on the Longitudinal Profile along Yellow River In Northeastern Tibetan Plateau

Previous studies indicate northeastern Tibetan Plateau is part of upward and outward growing plateau marginal front. Formation and evolution of the Yellow River during late Cenozoic here provides an ideal site to unravel the coupling process of the plateau uplift and river incision. Although some previous terrace studies within this region show the coupling pattern between the plateau uplift and Yellow River incision, more detailed analyzes are still needed to test the impact of the ongoing uplift and bedrock lithology on river longitudinal profile. And it is known that longitudinal profile of the Yellow River and tributaries can be adjusted to respond the vertical differential uplift and lithological change. To test the plateau uplift and lithologic impacts on river profile, present study was constructed for Yellow River and its 38 tributaries around Xunhua-Guide area. Our study indicates that 65.8%(25/38)of the longitudinal profiles are convex up, while 34.2%(13/38)show concave features. Determination of the knickpoint location along the profile indicates that 64.0%(16/25)of the 25 convex profiles have their knickpoints be near the basin boundary or the contact between basin and range systerm. Our preliminary fittings on logarithmic slope-area plots declare that 68.4%(26/38)are upward-convex and the left are almost near the linear state. Consequent analysis indicates that the longitudinal profiles are well controlled by the late Cenozoic tectonics and lithological difference, showing the landscape around Xunhua-Guide area is in the pre-steady state or near the steady state. Therefore, our findings also can support, to some degree, that the northeastern Tibetan Plateau is one of the newly uplifted parts when considering the whole plateau frame.