Origin and depositional characteristics of supported conglomerates

ZHANG Changmin,SONG Xinmin,WANG Xiaojun,WANG Xulong,ZHAO Kang,SHUANG Qi,LI Shaohua

Fig. 12. Principle of percolation and erosion of fine-grained sediments on the gravelly riverbed (modified after Reference [43]). (a) Openwork gravels are formed on gravelly riverbed; (b) Grain-supported and multi-scale grain-supported gravels are formed by filtration of fine-grained sediments into the pores of supported gravels; (c) Fine-grained materials form incrustation on the surface of gravel layer, which prevents the continuous infiltration (with grain-supported gravel texture preserved in the lower part of the gravel profile and the multi-scale grain-supported texture and matrix-grain-supported texture formed in the upper part); (d) The sand content in the current reduces, the water current erodes the riverbed, and the fine-grained deposits on the surface of gravel are eroded; (e) The water level drops below the surface of riverbed, and the fine-grained deposits between the gravels are carried to the downstream area to form a supported gravel texture again.