Morphologies of shallow
marine carbonate-forming environments
The term ‘carbonate platform’ can be generally applied
to any shallow marine environment where there is an
accumulation of carbonate sediment. If the platform is
attached to a continental landmass it is called a carbonate
shelf (Fig. 15.2), a region of sedimentation
that is analogous to shelf environments for terrigenous
clastic deposition. A carbonate shelf may receive
some supply of material from the adjacent landmass.
Carbonate banks are isolated platforms that are completely surrounded by deep water and therefore
do not receive any terrigenous clastic supply. A carbonate
atoll is a particular class of carbonate bank
formed above a subsiding volcanic island. Three
morphologies of carbonate platform are recognised:
they may be flat-topped with a sharp change in
slope at the edge forming a steep margin, either as a
rimmed or non-rimmed shelf, or they may have a
ramp morphology, a gentle (typically less than 1°)
slope down to deeper water with no break in slope
(James 2003).