Modern Non-Seismically Induced Deformation Bedding in the Lower Reaches of the Yellow River and Yellow River Delta

Key words: 
• deformation bedding /
• convolute bedding /
• genesis /
• non-seismic /
• Yellow River

Abstract: Deformation bedding is a relatively common and important example of a particular type of soft sediment deformation structure (SSDS). These have recently been the research focus of various disciplines, such as sedimentology, engineering geology, seismology and structural geology. The main difficulty and problem at present concerns the recognition of seismic and non-seismic SSDS. A large number of studies have shown a considerable amount of deformation bedding in the lower reaches of the Yellow River, and there is strong evidence that it is by no means always the result of earthquake activity. The study of deformation bedding in detail is of importance for developing identification and division criteria between seismic and non-seismic SSDS.
There are many types of deformation bedding from different causes in the Yellow River and distributary channels:typical convolute bedding and very irregular general deformation bedding, whose origins include density or gravity inversion, or sliding caused by wave action, or water and sliding sediments traction, or even dragging or pressure carving by blocks of ice. Deformation bedding from different causes each has unique geometrical features that are useful as reliable markers of its genesis, and which may also be used as reliable criteria for recognizing its seismic (or non-seismic) origin. In addition to the complex hydrodynamic and climatic conditions of the lower Yellow River, the development of deformation bedding is mainly related to the extremely fine particle size of the sediments.