Inversion of bedrock channel profiles in the Daqing Shan in Inner Mongolia, northern China: Implications for late Cenozoic tectonic history in the Hetao Basin and the Yellow River evolution

Abstract

Many studies indicate the Hetao Basin in Inner Mongolia, northern China, controlled the erosion base level of the upper Yellow River before 1.5 Ma. The late Cenozoic extensional rifting in the Hetao Basin in response to the northeastward growth of the Tibetan Plateau may be an plausible mechanism that initiated the headward erosional signal along the Yellow River at the northeastern margin of Tibetan Plateau ~1.8 Ma ago. However, little attention has been paid to establish the relationship between the late Cenozoic tectonic evolution in the Hetao Basin and integration of the upper Yellow River. In this paper, we explore the tectonic mechanism that can drive headward erosion along the Yellow River and the timescales over which it occurred by reconstructing the late Cenozoic tectonic history in the Hetao Basin. We applied linear inversion of bedrock channel profiles and late Cenozoic sedimentary strata in the Daqing Shan to explore the late Cenozoic tectonic evolution in the Hetao Basin. Results show that the accelerated vertical slip between the Daqing Shan and the Hetao Basin initiated at 2.8 ± 0.8 Ma, and the average relative uplift rate was 0.18 ± 0.04 mm/yr since 2.8 Ma. The lowering of erosion base level in the Hetao Basin since 2.8 ± 0.8 Ma produced a headward erosional signal along the Yellow River that initiated fluvial incision at the northeastern margin of the Tibetan Plateau ~1.8 Ma ago. That indicates the accelerated extensional rifting in the Hetao Basin has been responsible for the integration of the upper Yellow River since the late Pliocene. Our study improved understanding how the Yellow River responds to the late Cenozoic rifting around the Ordos Block, as well as the northeastward growth of the Tibetan Plateau. Meanwhile, these tectonic processes were also linked together by the Yellow River evolution.