Fig. 3

Outcrop photographs of the Zhushadong Formation. a Overview of the Zhushadong Formation succession in the Guankou section in Dengfeng area; the yellow dashed lines show the contacts between laminated dolostones (Member I and Member III respectively) and bioturbated limestone (Member II); b The lower laminated dolostone (Member I) preserves primary fabric, characteristic of algal and parallel lamination; c Stromatolites developed locally in the lower laminated dolostone (Member I); d Burrow filling of Thalassinoides in Member II is gray to black; matrix is light gray; e Chert (indicated by the arrow) is developed locally in the upper laminated dolostone (Member III)