Petrofacies analysis and depositional environment of the Jahrum Formation (Eocene), south-southwest of Burujen, Iran

Abstract

A progressive carbonate environment from supratidal to near-shore, retricted to intertidal and restricted shallow marine environment existed during deposition of the Jahrum Formation. The main facies characteristics of the Jahrum Formation in the study area are: (1) a laminated, unfossiliferous dolomite and pelleted dolomitic mudstone with solution collapse breccias; (2) a pelleted laminated fossiliferous dolomitic mudstone; (3) reworked skeletal wackestone to packstone; (4) highly reworked biointraclastic grainstone; (5) fossiliferous wackestone to packstone. As a result, two major depositional systems tracts can be defined: (1) the lower portion, are transgressive systems tract; and (2) the upper portion, as highstand systems tract. Diagenetic processes involved in supratidal rocks of the Jahrum Formation reflect dolomitization of initial sediments, leaching of calcium sulfate and carbonate grains, replacement of dolomite and stylolitziation. Voids are the most common pore type, and porosity was controlled by diagenesis that was influenced by primary depositional texture.