313
9.2
Marine Environments of Carbonate Production and Accumulation
thick sediment wedges of Holocene age at the
fringes of the platforms. Milliman (1993) estimates
that only one half of the carbonate accumulates
on shallow platforms where it is produced (2⋅10
12
mol yr
-1
), while the other half leaves the shallow
water environment in the form of sediment lobes
or wedges downslope.
Continental shelves
Only very little knowledge exists concerning the
quantitative carbonate production, export and its
accumulation on continental shelves. Two shelf
types, carbonate-rich and carbonate-poor shelves,
are distinguished by Milliman and Droxler (1996).
Fig. 9.1 Marine calcium carbonate accumulation in a) typical depocenters in shallow waters and b) their global
distribution (James and Clarke 1997).