Morphology And Genesis Of Non-Skeletal Components Of Samana Suk Formation, Shah Alla Ditta, Islamabad, Pakistan

Abstract

This study is focused on the morphology and genesis of non-skeletal components, and the interpretation of the depositional environment based on the concretions and non-skeletal grains. The study area is located in the Shah Alla Ditta neighborhood of Islamabad, Pakistan. Since the studied region is topographically near to the MBT, it has seen significant deformation. North-East Trending Anticlines define the research region. The Samana Suk Formation consists of well bedded limestone which is light brown to grey in color. The Samana Suk Formation includes brachiopods, belemnite, micritic beds and Oolitic limestone. The Concretions and non-skeletal grains interpreted are; 1) Ooid grains are further classified as Micritic Ooids, Concentric Ooids, Radial, Superficial Ooids, Broken Ooids, and Deformed Ooids. Characterized by well-rounded to sub-rounded and differ from each other on the basis of a number of cortices and the structures of the Ooids, the environment of deposition for the ooids ranges from a lower intertidal to a lagoonal environment. 2) Based on the state of transformation, aggregates and grains have been classified as grapestones. Grapestones are sub-rounded and lightly sorted grains. The characteristics indicate a platform to marginal reef marine environment. 3) Peloids grains are further classified into two types: Fecal Pellets and Other Pellets. They are distinguished by elongated rod-like to angular-shaped grains generated by micro-organism burrowing. Grapestones are sub-rounded and lightly sorted grains. The present features indicate an upper to middle intertidal shallow marine environment. Concretions and non-skeletal grains are deposited in a variety of environments, ranging from the intertidal zone to marginal reef zones. The importance of these concretions and non-skeletal grains is such that their existence or absence may indicate changes in sea level, these grains can be used for correlations on a regional scale, and Specific depositional settings can be interpreted on the basis of abundance and type of grains present, carbonate concretions and Grains are economically significant, and their geometries have a considerable impact on the reservoir characteristics of carbonate rocks.