• ATLAS INDEX

Carbonate Rock Classification

Terminology

CLASSIFICATION BASED ON DEPOSITIONAL TEXTURE (after Dunham, 1962 with modification by Embry and Klovan, 1971) AND MODIFICATIONS FOR DIAGENETIC TEXTURE (Wright, 1992; Flügel, 2004)

Depositional grainy allochthonous

Original components not organically bound during deposition
(Dunham, 1962; Wright, 1992)

Carbonate mud matrix-supported
  • Less than 10% grains
    • CALCI-MUDSTONE

 

  • More than 10% grains
    • WACKESTONE
Grain-supported
  • Carbonate mud matrix (silt and clay-grade) between the grains
    • PACKSTONE

 

  • Cement filling the interparticle pore space and/or open interparticle porosity; no carbonate mud matrix.
    • GRAINSTONE

Original components not organically bound during deposition. Reworked and transported skeletal and non skeletal grains of which more than 10% grains > 2 mm (Embry and Klovan, 1971)

Carbonate mud matrix-supported
  • Grains floating in carbonate mud matrix
    • FLOATSTONE
Grain-supported
  • Carbonate mud matrix (silt and clay-grade) between the grains
    • RUDSTONE/PACKSTONE

 

  • Cement filling the interparticle pore space and/or open interparticle porosity
    • RUDSTONE/GRAINSTONE

 

Original components not organically bound during deposition. Reworked and transported lithified carbonate rocks as intraclasts, carbonate lithoclasts and extraclasts (Flügel, 2004)

Angular clasts > 2 mm
  • Carbonate BRECCIA
    • Matrix-supported breccia
    • Clast-supported breccia with cement or matrix within interparticle space

 

  • Clasts formed within the basin due to syn-sedimentary processes
    • Intraformational breccia

 

  • Matrix supported with clasts up to metre-size
    • Megabreccia
Angular clasts < 2 mm
  • Microbreccia
Rounded clasts
  • CONGLOMERATE

Depositional biological autochthonous

Original components organically bound during deposition (Dunham, 1962; Embry and Klovan, 1971)

BOUNDSTONE
  • Organisms build a rigid framework (e.g., corals)
    • FRAMESTONE

 

  • Organisms act as baffle (e.g., algae, bryozoans)
    • BAFFLESTONE

 

  • Organisms encrust and bind (e.g., red algae)
    • BINDSTONE

 

  • In situ accumulation of organisms with plate, blade, leaf or cup-shaped (e.g., bryozoans, phylloid algae, Halimeda; Davies and Nassichuk 1990; Flügel 2004).
    • PLATESTONE

 

  • Precipitated carbonate mud (micrite, microsparite), peloids, laminae and crusts as result of biologically induced/influenced precipitation in presence of microbial mats (microbes, biofilms EPS extracellular polymeric substances).
    • AUTOMICRITE/ CLOTTED PELOIDAL MICRITE/ MICROBIAL BOUNDSTONE
    • PELOIDSTONE

 

  • Main component is cement associated with delicate organisms that serve as scaffolds for rigid cement crusts (eg., bryozoans; Webb, 1996)
    • BIOCEMENTSTONE

Diagenetic

Non obliterative (Wright, 1992)

Main component is cement

— CEMENTSTONE

Many grain sutured contacts as micro-stylolites
  • Some carbonate mud matrix (silt and clay-grade) between the grains
    • CONDENSED PACKSTONE

 

  • Some cement filling the interparticle pore space
    • CONDENSED GRAINSTONE
Most sutured grain contacts as micro-stylolites

— FITTED GRAINSTONE

Obliterative (Wright, 1992)

Crystals > 10 µm

— SPARSTONE

Crystals < 10 µm

— MICROSPARSTONE

Depositional texture not recognizable (Dunham, 1992)

— CRYSTALLINE

Dolomite > 50%

— DOLOMITE/ DOLOSTONE