Depositional Environment and Diagensis of Sakesar and Chorgali Formations, Exposed at Chorgali Pass, Khair-e-Murat Range, Punjab Pakistan (T-1354) (MFN 2233)

Abstract

The study is based on the petrographic analysis of 13 outcrop samples of Sakesar and Chorgaii Formations. exposed at Chorgali Pass. Khair-t:-Murat Range. The 7 outcrop samples were of Sakesar Fonnation and 6 outcrop samples were of Chorgali Formation. The Sakesar and Chorgali Formations. at this location. consists mostly of benthonic forams. green algae and gastropods shells. embedded in the calcic and dolomitic matrix. Thus the carbonates of Sakesar Formation are represented by biocalastic wackestoncs and packstones while Chorgali Formation is represented by dolomitic mudstones. 13 samples (7 from Sakesar Formation and 6 from Chorgali Fonnation) were collected at different horizons. Vugs and molds are present, indicating the dissolution of bioclasts. which were subsequently filled with calcite and quartz. Fractures are also present in both the fom1ations due to the intense tectonic activity in whole basin. No effective primary porosity was observed in both the fonnations, but the secondary porosity developed due to the open vugs. molds and fractures in Sakesar and Chorgali Formations. was observed. Abundance of benthonic forams indicates relatively shall0"" marine environment of deposition of carbonates of Sakesar Formation and dolomitic mudstone indicates Intratidal TO Supratidal environment of deposition of Chorgali Formation. Styloli1es have been fonned in the Sakesar as well as Chorgali Formation. Dolomitized beds were observed in both the fonnations. The transition between the Sakesar and the Chorgalj Formations are best seen at the Chorgali Pass. ll1ere is a change from a shallow. fully marine environment to an il1lenida]isupratidal environment.