Depositional And Diagenetic Setting Of Jurassic Carbonates, Thandiani Section, Hazara Basin, Pakistan: Implications On Reservoir Studies

Abstract

The Thandiani Section of the Abbottabad Group of Samana Suk Formation is selected for research study. The research is centered around the examination of rock characteristics, specifically through petrographical analysis involving microfacies and observed diagenetic features. The findings from the study of deposition and diagenesis indicate that the majority of the region consists of dense and compacted, fine to coarse-grained dolomitic limestones. In certain areas, dolomite forms as a secondary diagenetic feature. The limestone displays a light grey color on fresh surfaces and a light brown hue on weathered surfaces. It varies in size, with some areas exhibiting large, planar, and fossil-rich deposits that range from thin to medium to thick-bedded. During our field investigation, we observed and documented various features such as stylolite fractures, calcite veins, and calcite patches. By analyzing photomicrographs, a comprehensive depositional model of the microfacies has been developed, illustrating that these microfacies were deposited within the inner portion of a homoclinal ramp, transitioning from a lagoon to shallow marine environments.