MICROFACIES ANALYSIS OF LATE JURASSIC SAMANA SUK FORMATION, HAZARA BASIN LESSER HIMALAYA NORTH PAKISTAN

Abstract

The detailed petrological investigation of Samana Suk Formation from Hazara Basin, Pakistan was carried out to elaborate its microfacies. The Samana Suk Formation is mostly composed of fine to coarse-grained, limestone with dolomite in parts developed as a secondary diagenetic fabric. Twenty-five samples were studied from Thandiani Section, and five microfacies with seven sub microfacies were identified. The identified microfacies include Peloidal Foraminiferal Mudstone, Ooidal Peloidal Mudstone, Bioclastic Planktonic Mudstone as Submicrofacies, Peloidal Wackstone, Ooidal Wackstone, Intraclastic Wackstone as Sub Microfacies, Peloidal-Packstone Microfacies, Ooidal Mud-Wack Microfacies and Peloidal-Ooidal Wack-Pack Submicrofacies. Diagenetic features, such as Stylolites, Calcite Veins, Fractures, Dolomitization, Cementation, Compaction and Micritization have been observed in the petrographic study of the samples. The environment of deposition as depicted from the microfacies is Outer ramp for Mudstone, Peloidal Foraminiferal Mudstone, Ooidal to Peloidal Mudstone and Bioclastic Mudstone; Middle ramp for Peloidal Wackstone; Inner ramp for Ooidal Wackstone, Intraclastic Wackstone Peloidal Packstone and Peloidal-Ooidal Wack-Packstone; Inner-Middle ramp for Ooidal-Mud-Wackstone. Based on the microfacies analysis the Samana Suk Formation was interpreted to be deposited in a shallow shelf environment

Keywords

• sedimentology
• petrology
• diagenesis
• depositional environment
• thandiani.