Fig. 8From: Morphology and features of Cambrian oncoids and responses to palaeogeography of the North China PlatformSEM and EDX analyses of the light and dark laminae. a Various mineral structures of oncoids, with the two points of EDX analysis marked; b A cortex showing a bimineralic structure; c Local magnification of b, showing calcite crystals in the light laminae; d Local magnification of b, showing amorphous calcium carbonate mud in the dark laminae; e Two kinds of pyrite particles observed inside the oncoids: framboidal pyrite (pink arrows) and ordinary massive pyrite (yellow arrows); f, g EDX results of the two analyzed points in aBack to article page