Basin Analysis: Recognizing Depositional Settings - Microfacies of Carbonate Rocks - page 749

Table 15.1. General summary of criteria used in differentiating supratidal, intertidal and shallow subtidal carbonates. The
relative frequencies of diagnostic features should not be taken as the only possible truth!

Supratidal Intertidal Shallow subtidal

Sedimentary structures
Fine-scale lamination common abundant rare

Desiccation structures abundant abundant absent

Tepees abundant rare absent

Flat-pebble conglomerates rare common rare

Collapse breccias abundant abundant absent

Biogenic structures
Microbial/algal mats abundant abundant rare

Stromatolites rare abundant common

Burrows rare abundant abundant

Fenestral fabrics
Irregular and laminoid birdseyes abundant abundant rare

Tubular root voids abundant common rare

Sedimentary grains
Peloids common abundant common

Fecal pellets rare abundant abundant

Benthic peloids rare common absent

Mud intraclasts common abundant common

Black lithoclasts common common absent

Non-skeletal oncoids rare common common

Skeletal oncoids rare common common to abundant

Ooids absent common common

Cortoids absent common abundant

Aggregate grains absent common abundant

Biota: Characteristic groups
Benthic foraminifera very rare rare to common common to abundant

Ostracods rare rare common

Gastropods rare common to abundant common to abundant

Bivalves absent rare common

Calcareous algae absent rare common to abundant

Cyanobacteria common abundant common

Biota: Diversity very low low high

Diagenetic criteria
Gravitational cement abundant common absent

Meniscus cement common common absent

Vadose pisoids abundant rare absent

Carbonate surface crusts abundant common absent

Fine-grained dolomite common common common

Gypsum/anhydrite-carbonate abundant abundant rare

associations
Pedogenic structures

abundant rare absent

Evaporites
Gypsum, anhydrite and halite occurring in associa-
tion with peritidal carbonates are common in arid and
semiarid areas. Upper intertidal and supratidal sabkha
sediments are characterized by gypsum, landward ar-
eas by anhydrite nodules and chicken-wire anhydrite,
often hydrated to gypsum. See Pl. 125/2, 4.

formation connected with karstification in humid zones
and calichification in arid and semiarid zones (see Sect.
15.1 and 15.2).

15.5.1.3 Synopsis of Diagnostic Criteria

Lists of diagnostic peritidal features provided by vari-
ous authors including Shinn (1983), Hardie and Shinn
(1986) and Demicco and Hardie (1994), and the infor-
mation in the preceding section show that it is difficult

Pedogenic structures
Supratidal conditions characterized by prolonged
subaerial exposure are reflected by dissolution and soil