Genetic Mechanism of the Anti Z-Shaped Channel of the Yellow River in the Qinghai-Tibet Plateau
River evolution depends on regional geodynamic processes.The anti Z-shaped river course of the Yellow River in the northeastern margin of the Qinghai-Tibet Plateau flows through five major tectonic zones,with most of the river sections occurring in fault and fractured rock zones,and the channels are mostly distributed along the piedmont faults of the orogenic belt and at the junction of tectonic units.The NWW-trending faults control the long-line extension of the river channel,and the NE and NW trending faults control the short-line turning of the river channel,while the intersection of NE and NW-trending faults forms an oblique array swing extension of the channel.In the process of continuous NE-trending extruding of the Qinghai-Tibet Plateau,it is structurally manifested as NWW-SEE trending compound and super-imposed orogenic belt and geomorphologically expressed as alternating distribution of uplifts and depressions due to the joint obstruction of the Alashan and Ordos blocks,and the mainstream of the river is generally parallel to the distribution direction of the main structural belt.The activity of NE-trending tensional strike-slip fault is intensified when it is obstructed by Yangtze,Qinling and Ordos stable blocks,resulting in the river direction turning from the original SEE to NE in a short-line,large-angle manner,and driving the NW hanging wall of NE-trending tensional strike-slip fault to subside greatly,forming an inclined graben with high in the west and low in the east.However,the river is forced to flow back in NW-NWW direction after encountering the obstruction of the next new NWW-SEE trending fault zone,forming a unique ob-lique U-shaped large backflow of the Yellow River.The fault structure is the main controlling factor for the generation,evolution,extension,turning of the river channel and the formation of the anti Z-shaped river pattern.
Yellow Riveranti Z-shaped river patternfault controls on the river morphologyQinghai-Tibet Plateau
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