Page 235 - Carbonate Facies in Geologic History

222 Permo-Triassic Buildups and Late Triassic Ecologic Reefs

formed in a strongly seasonal and evaporitic climate and endured strong contem-
porary diagenesis and (2) major fluctuation of sea level exposed the platform, its
edge, and large parts of the slope periodically during Permian time.
The following key microfacies types are recognized and illustrated by Dun-
ham (1972).
Pm 1. Spiculitic, radiolarian laminated calcisilt-packstone in beds of dark, platy limestone.
Basinal, Facies belt 1. Standard microfacies type 1; Dunham, 1972, Figs.III-4-7.
Pm2. Brown finely bioclastic packstone; from lower slope facies, deep shelf margin, Facies
belt 3; standard microfacies type 2; Dunham, 1972, Fig. III-3.
Pm3. Lithoclastic bioclastic packstone beds within coarser marine talus breccia; very fossil-
iferous with open marine biota, on foreslope of carbonate platform, Facies belt 4;
standard microfacies type 4; Dunham, 1972, Fig. III -8-13.
Pm4. Typical micrite of organic buildup with sponges, Facies belt 5. Microfacies type 7-
baffiestone; Dunham, 1972, Fig. II-55.
Pm5. Typical micrite of organic buildup with stromatolite-lined cavities, and encrusting
organisms (Tubiphytes, spongiomorphs). Facies belt 5; standard microfacies type 7-
bindstone; Dunham, 1972, Fig. II-59 (Plate XXVB).
Pm 6. Typical micritic bioclastic wackestone associated with vuggy boundstone of organic
buildups, Facies belt 5; standard microfacies type 9; Dunham, 1972, Figs. II-53-54-60.
Pm 7. Lime grainstone of oolite and coated grains, Facies belt 6; standard microfacies
type 11; Dunham, 1972, Figs.II-I-4.
Pm8. Lime grainstone with dasycladacean and large gastropod particles, Facies belt 6;
standard microfacies type 18; Dunham, 1972. Fig. II -48, Figs. 1-2-5.
Pm 9. Lime grainstone, fusulinid coquina, Facies belt 6; special variety of standard microfa-
cies type 12; Dunham, 1972, Fig. II-49, Fig. 1-6.
Pm 10. Lime grainstone-pisolites, showing evidence for in situ growth; considered a diage-
neticfacies; Dunham, 1972, Fig.II-33-35 (Plate XVB).
Pm 11. Lime mudstone-wackestone with peloids and ostracods, mollusks, and calcispheres,
Facies belt 8; standard microfacies type 19; Dunham, 1972, Figs. 1-43,55.
Pm 12. Lime mudstone-wackestone with well-developed fenestral fabric, Facies belt 8; stan-
dard microfacies type 19; Dunham, 1972, Fig. 1-36 (Plate XIII A).

Table VIII-1. Facies Belts Permian Reef Complex

General facies Wilson's facies belt Tyrell (1969), Dunham (1972) microfacies
name (Meissner, number and name designation
1972)

Bernal Red shale and siltstone

Chalk Bluff 9. Platform Evaporites; gypsum (parallel bedded,
evaporite laminated, interbedded with fine sandstone)
and dolomite wackestone

Carlsbad 8. Facies of restricted Mixed carbonate environments; dolomite
circulation on marine wackestone with calcispheres and ostracods,
platform algal stromatolitic mudstone, unwinnowed
shelf sand, pelletoidal dolomite grainstone.
(Many marine to meteoric vadose sedi-
mentary-diagenetic structures e.g., fenestral
fabric, pisolites, tepees.)