lower part of the Zhangxia Formation (Crepicephalina Zone: Drumian of Cambrian Series 3). The coralomorph-bearing lithistid demosponge-microbial reefs are intercalated within bioclastic wackestone beds. Thin veneers of stromatolites. In places, sheet-like micrite layers and knobshaped stromatolites consisting of vesicular and globular clots pave the
underlying wackestone. The underlying wackestone was stabilized by microbial consolidation, which then provided suitable substrates for the microbial reefs. Bioclastic wackestone is thus conformably overlain by the basal parts of the microbial reefs.