Biostratigraphy and Microfacies Analysis of Sakesar Formation in Nammal Gorge, Western Salt Range, Upper Indus Basin, Pakistan (P-0968) (MFN 5544)

Abstract

The Sakesar Formation in Nammal Gorge, Western Salt Range, Pakistan was investigated to elaborate its Biostratigraphy, Microfacies and diagenetic settings. The Formation is widely distributed in the Salt Range and is composed of thin to thick bedded nodular Limestone, with minute distribution of shale, marls and chert in the upper part. It has a conformable lower contact with Nammal Formation. A detailed study was conducted after collecting 15 rock samples in vertical thickness of approx. 18.2m. Thorough detailed field observations and laboratory investigations revealed that the Sakesar Formation contains four Microfacies i.e. Bioclastic mudstone facies, Algal Miliolin mudstone and wackstone facies, Bioclastic wackstone facies and Nummulitic wackstone and packstone facies. A number of larger benthic Foraminifera i.e. Nummulites mamillatus (Fichtel and Moll), Nummulites atacicus (Leymerie), Nummulites globulus (Leymerie), Assilina subspinosa (Davies and Pinfold), Assilina laminose (Gill), Viviparus malleatus, Alveolina eliptica, Lockhartia conditi (Nuttall) and Assilina granulosa (d’Archiac). Research work also illustrates various cement types i.e. Micritic envelops, Aragonite dissolution, Isopach bladed cement and sparry calcite. Vertical variation in the studied sections indicates repetition of the interpreted environments. Microfacies analysis and digenetic settings leads towards the conclusion that formation was deposited in shallow shelf environment with different digenetic settings.