BIOSTRATIGRAPHY AND MICROFACIES OF THE UPPER CRETACEOUS KAWAGARH FORMATION, GARHI HABIBULLAH SECTION, HAZARA BASIN, KHYBER PAKHTUNKHWA, PAKISTAN

Abstract

This research is focused on the petrographic investigation of the Cretaceous Kawagarh Formation exposed in Garhi Habibullah section of Hazara Basin. The Formation is composed of thick to medium bedded, hard, highly fractured, argillaceous and marly limestone with steep dip angles. A total of 17 representative samples were collected at regular interval of 5meters for petrography. In petrography, a large number of fossils of planktonic foraminifera, radiolarians, bioclasts, sparite, micrite and matrix were identified. On the basis of these features four microfacies including planktonic foraminiferal wackestone, planktonic foraminiferal mudstone, bioclastic mudstone and radiolarian bioclastic wackestone were established. The environment of deposition for the formation is concluded as outer ramp to deep basins. The biozone in this study for the Kawagarh Formation is globutruncana ventricosa biozone revealing the age of the formation as early to middle Campanian. The recorded diagenetic processes include cementation, pyritization, micritization, fracturing, pressure dissolution and neomorphism are common in the rock unit. These diagenetic features impart vuggy porosity to the formation, but the reservoir potential of the Kawagarh Formation is relatively poor due to diagenetic episodes. Thus, the Kawagarh Formation, Garhi Habibullah section, is an early to middle Campanian age with poor reservoir properties.