Depositional Environment and Diagenesis of Nammal Limestone, Exposed in Nammal Corge, Western Salt Range, Punjab, Pakistan

Abstract

The present study is based on the petrographic analysis of outcrop samples of Nammal Limestone, exposed in Nammal Gorge. The Nammal Limestone, at this location, consists of mostly broken pieces of planktonic forams with sparse benthonic forams and ostracodes, embedded in the groundmass of micrite and some marl. Thus the carbonates of Nammal Formation are represented by bioclastic packstones and wackestones.

Abundance of planktonic forams indicates relatively deep marine environment of deposition of carbonates of this formation. Chemical compaction has resulted common occurrence of microstylolites during diagenesis. Sparite filled molds are locally present, indicating dissolution of bioclasts, which subsequently filled with calcite cement. No effective primary or secondary porosity was observed within the limestones of Nammal Formation.