Page 388 - Carbonate Facies in Geologic History

Review of Tectonic Settings for Carbonate Buildups and Cycles 375

l. M. U.
. .. + + + + + + + + + .. . . . + + + + + .
TYPE OF ORGANISM PALEOZ. PALEOZ. PALEOZ.MESOZOIC CENOZOIC
BLUE GREEN ALGAE <C:. + + + • + + + + + . . . ..
RED ALGAE MASSIVE .. . . + ... + + •
+
PLATY GREEN ALGAE + + ... .. + + + + + + + .. + + +
....:..-
-
ENCRUSTING TUBULAR <:'"): ~+ +"",*-+ + +. + · .
FORAMS
· ..
. .
. ...
TUBIPHYTES -<": "8>
..
~ . ++~
~
SPONGES ... . .. + + + +
-
+ + + +
HYDROZOANS ooe;::: ...... +. + + -.- + + + + + . . .
. ''- + + + +
-
Tabulates ~ .. , '--.. ~
+ + He;;
CORAL ~ ~++/ ,.;.-- ......... ~+ra)s: + : + : +
Col. Rugose
.>
+ + + "':'"
ENCRUSTING BRYOZOANS ~ . .:.--::::
Fenestrate bryozoan c( r--c....+ + + + ..
+
-<
~+ + + + + +
+ + + +
RUDIST BIVALVES
Fig. XII -6. Dominance of major organic groups in carbonate buildups through geologic time.
After Heckel (1974)
In addition, special groups important in sediment binding and trapping dominate
at certain periods in the geologic record. For example, colonial and encrusting
foraminifera from Devonian to Jurassic, bryozoans in the Ordovician and Early
Carboniferous, and rudists in the Cretaceous.
Review of Tectonic Settings for Carbonate Buildups and Cycles
Major amounts of carbonate generally do not accumulate in areas of extensive
tectonic activity except for some isolated reefs in geosynclines. This is because
orogenic uplift tends to cause intense erosion and produces in humid regions a
considerable influx of fresh water and terrigenous clastics which suppress general
carbonate production. Inasmuch as tectonic activity does not control source area
and rate of deposition in the carbonate realm as in terrigenous clastic sedimenta-
tion, a lack of precise correlation between tectonics and carbonate deposition
might be expected. Other controlling parameters are of equal or greater impor-
tance in shaping the major types of carbonate sediments. Nevertheless, megatec-
tonic elements such as geosynclines, basins, and cratonic areas may serve as a
useful framework for grouping carbonate facies patterns even though such groups
may not be as sedimentologically distinctive as one would wish.
The relationships which exist between the outlined tectonic settings and the
major groupings of carbonate patterns used in this volume are expressed on
Tables XII-l and XII-2.
Subcategories in the classification below are based on form and trend of the
buildups as well as their facies, parameters which are related to the degree of