Reef limestone predominately developed with limy mudstone present at the basal part. The platform margin reef (bank) is located in a transition zone between the platform and the deep- or deeper-water slope, with the water depth at and near the wave base, where good circulation of water body is available. This environment provides a strong hydrodynamic force, due to the joint control of wave and tidal, and hence allows grain-dominated bank facies bodies to deposit, with locally present organic reefs formed by substantial in-situ biogroups.