GST ool |
Oolitic grainstone |
Composed of ooids well-sorted (300 to 500 µm), peloids (100 to 200 µm) and aggregate grains (1 mm), showing partial to total micritization. Two cementation phases: acicular fringe, which keeps open the framework during eodiagenesis, and mosaic, which obliterates almost all intergranular pores. |
Oscillatory subaqueous flow associated with reworking by fair weather wave good orbitals |
GST onc |
Oncolitic grainstone |
Composed of oncoids well-rounded and well-sorted, from 500 to 700 µm, whose cores are composed of echinoids and benthic foraminifera. It also occurs aggregate grains, ooids, peloids and rare bioclasts. Acicular cement, locally dissolved or detached do grão (mechanical compaction). Pores enlarged by dissolution, sometimes creating vugs. |
Oscillatory subaqueous flow associated with reworking by fair weather wave good orbitals. The encapsulation of bioclasts occurs because cyanobacteria films activity. |
GST onc pel |
Oncolitic peloidal grainstone |
Composed of coarse portion (> 2 mm), which contains subrounded to irregular aggregate grains, produced by oncoids agglutination; and medium/fine portion (100 to 200 µm), composed of peloids, mollusk fragments (< 500 µm) and rare benthic hyaline foraminifera. The edges of oncoids and bioclasts are micritized. Pores enlarged by dissolution or filled by a drusy mosaic/granular cement. |
Oscillatory subaqueous flow associated with reworking by fair weather wave good orbitals in protected environment. The encapsulation of bioclasts occurs because cyanobacteria films activity. |
PCK onc bio |
Oncolitic bioclastic packstone |
Composed of oncoids (500 µm), microncoids e peloids (100 µm), echinoids and benthic hyaline foraminifera in a micritic matrix. Echinoids showing syntaxial overgrowth. |
Oscillatory subaqueous flow associated with reworking by fair weather wave good orbitals in protected environment. Intercalation with decantation periods. |
PCK pel bio |
Peloidal bioclastic packstone |
Composed of oncoids (500 µm), microncoids e peloids (100 µm), echinoids and benthic hyaline foraminifera dispersed in matrix. Echinoids showing syntaxial overgrowth. Dissolution creates bioclasts molds and enlarges pores. |
Oscillatory subaqueous flow associated with reworking by fair weather wave good orbitals in protected environment. Intercalation with decantation periods. |
PCK bio |
Bioclastic packstone |
Fragments (> 2mm) of mollusks, echinoids, benthic agglutinated and hyaline foraminifera dispersed in a micritic matrix. Pithonelids, planctonic foraminifera and opaque minerals are rare. |
Rip currents in storm events/ Episodic gravity flow |
WCK/PCK ool |
Oolitic wackestone/ packstone
|
Ooids (500 µm) and red algae (1 mm) dispersed in carbonate matrix rich in pelagic elements (pithonelids as Pithonella sphaerica, planctonic foraminifera as Favusella washitensis e Hedbergella sp.) and echinoids fragments. |
Rip currents in storm events/ Episodic gravity flow |
WCK |
Wackestone |
Mostly composed of matrix, containing bioclasts (pithonelids and echinoids) and sometimes euhedral dolomite crystals. |
Subaqueous decantation |
WCK pit |
Pithonelid wackestone |
Mostly composed of matrix, containing pithonelids (Pithonella sphaerica e P. ovalis) and radiolarians. Benthic and planktonic foraminifera, echinoids fragments are rare. It occurs framboidal pyrites. |
Subaqueous decantation |
WCK bio |
Bioclastic wackestone with glauconite |
Mostly composed of matrix, containing angular detrital quartz grains, rounded glauconite grains, echinoids and rare pithonelids. |
Subaqueous decantation associated with very low sedimentation rate |
DOL |
Dolomite |
Brownish to gray dolomite, which are composed of euhedral dolomite crystals (100 µm). |
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