Pict. 1.6. Permian black, bitumenous limestone Pict. 1.7. Pleistocene limestone The Folk classification use the type of components to classify limestones. Allochemical are those that contain grains brought in from elsewhere (i.e. similar to detrital grains in clastic rocks). Orthochemical rocks are those in which the carbonate crystallized in place. Allochemical rocks have grains that may consist of fossiliferous material, ooids, peloids, or intraclasts. These are embedded in a matrix consisting of microcrystalline carbonate (calcite or dolomite), called micrite, or larger visible crystals of carbonate, called sparite. Sparite is clear granular carbonate that has formed through recrystallization of micrite, or by crystallization within previously existing void spaces during diagenesis. The name of the rock contains the type of the orthochemical and allochemical components (example oosparite, biomicrite) (Báldi 1991, Haas 1998) (Table 1.2.). Rocks >10% <10% of of reefs component and <1% allo- >25% intramicrite micrite or dismicrite (if it contains micrite sparite) with <25% >25% oosparite ooid content <25% ooid >3:1 bioclasts between 3:1 micrite and 1:3 with fossil biolithit content peloids <1:3 micrite with peloid content Table 1.2. Classification of limestones after Folk (1959, 1962) The Dunham classification is based on the concept of grain support. The classification divides carbonate rocks into two broad groups, those whose original components were not bound together during deposition and those whose original components formed in place and consist of intergrowths of skeletal material (Table1.3.).
Pict. 1.6. Permian black, bitumenous limestone Pict. 1.7. Pleistocene limestone The Folk classification use the type of components to classify limestones. Allochemical are those that contain grains brought in from elsewhere (i.e. similar to detrital grains in clastic rocks). Orthochemical rocks are those in which the carbonate crystallized in place. Allochemical rocks have grains that may consist of fossiliferous material, ooids, peloids, or intraclasts. These are embedded in a matrix consisting of microcrystalline carbonate (calcite or dolomite), called micrite, or larger visible crystals of carbonate, called sparite. Sparite is clear granular carbonate that has formed through recrystallization of micrite, or by crystallization within previously existing void spaces during diagenesis. The name of the rock contains the type of the orthochemical and allochemical components (example oosparite, biomicrite) (Báldi 1991, Haas 1998) (Table 1.2.). of >10% <10% component Rocks of reefs and <1% allo- >25% intramicrite micrite with content micrite or dismicrite (if it contains sparite) <25% >25% ooid oosparite <25% ooid >3:1 bioclasts micrite with fossil content between 3:1 and 1:3 biolithit peloids micrite with peloid content <1:3 Table 1.2. Classification of limestones after Folk (1959, 1962) The Dunham classification is based on the concept of grain support. The classification divides carbonate rocks into two broad groups, those whose original components were not bound together during deposition and those whose original components formed in place and consist of intergrowths of skeletal material (Table1.3.).
2011-0038_37_david1_en.docx