Page 360 - Carbonate Facies in Geologic History

Facies Patterns 347

dant, large, elongate, foraminifera of genus Praealveolina (Plate XXX A). Offbank
deposits consist of several facies; in sequence, away from the bank, these are:
1. Pure lime wackestone with mollusks, echinoids, and Orbitolina or marls with
oysters, clams, and echinoids.
2. "O/igostegina" (calcisphere) limestone and marls.
3. Globigerinid marls.
4. Dark, bituminous, spiculitic radiolarian-bearing siliceous limestone and shale
in the Zagros geosynclince basins.
The Cenomanian facies are thus like those of the Albian-Aptian with the
notable addition of the alveolinid foraminifera in the bank deposits and the
calcispheres in the immediate slope or bank margin marls. As in the Albian,
identical microfacies are known in Mexico.