Figure 4

Outcrop and microscopic characteristics of Bingmagou Formation rocks in the Shaoyuan and Mianchi regions. (A and B) Grain-supported conglomerate in the Shaoyuan region, with a complex gravel composition, various grain sizes, poor sorting, poor roundness, and no obvious sedimentary structures. (C) Matrix-supported conglomerate in the Mianchi region, with oriented gravel clasts (long axis parallel to the bedding plane). (D) Grain-supported conglomerate in the Mianchi region without obvious sedimentary structures, in which gravel clasts are mostly quartzite and gneiss. (F) Conglomeratic sandstone in the Shaoyuan region; the conglomeratic sandstone is interbedded with layered sandstone, and the gravel clasts exhibit directional arrangement. (E and H) Conglomeratic sandstone in the Mianchi region, in which the gravels are complex in composition and arranged along the scoured surface or bedding plane. (H) Wedged bedding, and laminations inclined unidirectionally within a single layer. (G) Purple shale interbedded with greyish brown fine argillaceous sandstone in the Shaoyuan region. (I) Red sandy mudstone in the Mianchi region. (J and K) Microscopic characteristics of argillaceous sandstone in a matrix-supported sandstone, in which the quartz grains are directionally arranged, angular to round, and poorly sorted. (J) Plane-polarized light. (K) Cross-polarized light.