Microfacies analysis and depositional environment of Maastrichtian – Eocene limestone of the Ukhrul district, Manipur, Northeast India

Abstract

Microfacies analysis of the carbonate rocks of Ukhrul were conducted to understand the sedimentological features, microfacies associations and depositional environment of the flyschoidal sediments deposited within Upper Disang Group. These rocks composed mainly of microcrystalline calcite matrix, sparry calcite cement, skeleton grains and shell fragments. Three microfacies were identified as mudstone, wackestone and packstone. Based on the energy index classification, these limestones can be categorized into subtype II₁ of type II those were deposited in an intermittently agitated environment. Foraminifera of Upper Cretaceous to Eocene age have been identified in the present study. The recognized microfacies of the present study have been compared and correlated with the standard microfacies association (SMA), and in all probability they falls in Facies Zone 8. The detail microfacies analysis show that the studied limestones were deposited in a shallow marine shelf condition with restricted to moderately agitated water within an interior platform basin during the Maastrichtian – Eocene time.

Key words: Microfacies, shallow water Carbonate, restricted environment.