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Choquette and Pray classification

Choquette and Pray classification A widely used, descriptive classification of porosity types developed in carbonates. Primary porosity types are classified as: interparticle—pores between the grains; framework—pore spaces between the rigid framework of carbonate skeletons, as in a reef; shelter—pore spaces preserved when curved shell fragments or irregularly shaped grains prevent intergranular spaces from becoming completely occupied by the mud matrix; intraparticle—pores within the skeletal material which do not become filled with diagenetic (see DIAGENESIS) cement; and fenestral—pores within carbonate muds provided by fenestrae. Secondary porosity types, produced by diagenetic and tectonic (see TECTONISM) effects, are classified as: intercrystalline—pores produced by dolomitization or by preferential dissolution of mineral cements; moldic—pore spaces produced by the dissolution of grains, e.g. ooids, shell fragments; channel and vug—both produced by the dissolution of the rock by formation waters to generate linear (channel) or patchy (vug) cavities; cavern—the largescale dissolution of the rock to yield man-sized or larger pores; and fracture—formed by tectonic stresses within the rock.

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