Classification – A Name for Your Sample - Microfacies of Carbonate Rocks - page 341

Fig. 8.1 . Autochthonous carbonates . A - Reef rock types (Embry and Klovan 1971). The boundstone category is subdivided
into bafflestone, bindstone, and framestone (Pl. 41 and Pl. 42; see Box 8.1 for definitions). The use of these names requires
a decision on whether or not the fossil organisms bound the sediment during deposition and if so, in what manner. Frame-
stone, bindstone, and bafflestone, therefore, are highly interpretative rock types. Floatstone and rudstone designate lime-
stones with transported grains larger than 2 mm (Pl. 45). B - Roles of organisms in the construction of reef carbonates. Note
that framestone fabrics can originate from supporting, secondary stabilizing, and cementing. Bindstone fabrics are formed by
binding, stabilizing, and microbial micrite. After Tsien (1994). C - Dependence of reef rock types on environmental con-
straints of benthic communities. Reefal fabrics can be placed into four groups, which are united by the morphology of the
dominant members of the reef-building community: Laminar forms that stabilize sediment may form bindstones, cruststones
and coverstones; mutual encrusting, domal, and massive branching morphologies may give rise to framestones and
branchstones. Cup-shaped, stick or branched forms that accumulate sediment can produce bafflestones and branchstones.
Note that ecologically disparate communities may produce convergent rock fabrics. The distribution of reef biota is highly
dependent on nutrient availability, which has profound effects on the trophic structure and growth forms of reefbuilders, and
hence, on the resultant carbonate sediment and its fabrics. An important message from this model is that different hydrody-
namic energy levels are not the only and often not the most important causes of different reef rock fabrics. After Wood
(1993).