Dolomitization of Calcareous lithofacies in Ab-E Garm Area (Qazvin province)

In present study 29 samples collected from outcrops of Oligo-Miocene limestones in the Ab-E Garm area were prepared for petrograhic studies after staining with Alizarin Red S. and Potassium ferricyanide. These sediments copmrise different types of lithofacies including wackstone to boiclast mudstone, barren lime mudstones and foraminiferal bioclastic wackstone-packstones accompanying local distributions of algal boundstones. Two types of dolomite were recognized (microcrystalline and coarsely crystalline dolomites), located at the lower and middle part of the succession. The former is restricted to wackstone to boiclast mudstone and the latter occurs in the foraminiferal bioclastic wackstone-packstones, algal boundstone beds. Microcrystalline dolomite is interpreted as evaporative sabkha dolomite and coarsely crystalline dolomite as seepage-reflux dolomite that exrienced subsequent recrsytalization.