Carbonate rocks 1 Carbonate rocks are composed of two minerals Calcite CaCO 3 Dolomite Ca Mg (CO 3 ) The principal constituents of limestones are 1. Allochemical components (ooids, bioclasts, peloids and intraclasts) 2. Micrite (microcrystalline calcite: refers to a crystal size less than 5 um) 3. Sparite (sparry calcite; refers to crystals of 5 um or more in diameter)

2 Dunham classification of limestone

Carbonate rocks Ooid Grainstone 3

Carbonate rocks Ooid Packstone 4

Carbonate rocks Bioclast Packstone 5

Carbonate rocks Bioclast Wackstone 6

Carbonate rocks Intraclast Grainstone 7

Carbonate rocks Peloid Grainstone 8

Carbonate rocks Carbonate Mudstone 9

Carbonate rocks Dolomitic limestone (The original sediment is a peloidal packstone) 10 The matrix have been replaced by dolomite, showing its characteristic euhedral rhombic shape

Carbonate rocks Dolomitic limeatone 11 A limestone section which has been treated with Alizarine Red S. Calcite showing shades of pink, red, and brown. The dolomite is colorless to grey and appears to be replacing matrix and/or cement.

Carbonate rocks Dolomite rock or dolostone 12 Dolomitic carbonate are classified according to their dolomite content: dolomite 0-10% Limestone 10-50% dolomitic limestone 50-90% calcitic dolomite % dolomite

Carbonate rocks 12 THE END