Estimates of absolute depth can be made based upon integrated analysis of a variety of distinctive sedimentary structures related to exposure, indicators of position with respect to shoreline, normal wave base and storm wave base, and evidence of light-related zones (Brett et al.
Carbonates accumulated largely in situ, with micritic wackestones in shallow-water areas, skeletal, oncoid--and stromatoporoid-bearing grainstone facies in mid-ramp settings and muddy, nodular, brachiopod-dominated packstones with minor grainstone beds in areas below normal wave base to the north.
Sediments of these facies were deposited below normal wave base but within the shallow euphotic zone, as indicated by the presence of cyclocrinitid green algae (Beadle & Johnson 1986).
The feature of benthic fauna and stratigraphic relationships with the other microfacies suggest that marl facies were deposited in an open lagoon, calm, deep and normal-salinity water but the co-occurrence of planktonic and some benthic (Nummulitidae) foraminifera in the base of the Asmari marl and marly limestone, suggest that this facies was deposited in calm, low energy hydrodynamic and deep normal salinity water which indicates deposition below the storm wave base [69,19,22,28]
This microfacies show an environment between the storm wave base and fair-weather wave base [69,28].
This microfacies is interpreted to be formed by in-situ organisms as an organic reef (Bioherm) in margin of platform and was located above the fair-weather wave base (FWWB).
This suggests the megaripple sandstone/fine grained sandstone/siltstone interbed sequence formed in a fluctuating shallow-marine environment characterized by fluctuating energy conditions in which deposition alternated between just below and within wave base.
The presence of laminated siltstone, and associated Cruziana ichnofacies, interbedded with the megaripples, argues for deposition in shallow-marine conditions that fluctuated from wave base to just below wave base.
The condition of this environment is shallow, with medium to low energy and presence in the photic zone below the fair-weather wave base.
This lagoon environment is characterized by shallow, medium to low energy and presence in the photic zone below the fair-weather wave base.
So the Nummulites microfacies has been deposited below Fair weather wave base.
Mr Stuart Gibson, Bunkers Big Wave Base
Camp Goat Bluff, South Arm.