Microfacies analysis of the Palaeocene Lockhart limestone on the eastern margin of the Upper Indus Basin (Pakistan): Implications for the depositional environment and reservoir characteristics

A detailed sedimentological analysis of the Palaeocene Lockhart Limestone has been conducted to evaluate depositional environment, diagenetic processes and hydrocarbon potential eastern margin Upper Indus Basin. From bottom top, there are three microfacies recorded. The lower microfacies, composed fine-grained micrite some dolomite, reflect low energy calm palaeo-current in shallower section (1–2 m) inner shelf close shore. middle contain algae that suggest 5–15 m water depth, especially along inner-middle shelf, but fractured mixed bioclasts material indicate moderately active wave base. Progressing from a gradual shift orthochem allochem components is observed. top dominated by massive benthic microfossils, indicating moderate energy-water conditions with normal salinity. However, presence limestone intraclasts surrounded microspar, miliolids nummulites at indicates high-energy environment increasing salinity depths 20 130 m. These findings show was deposited shallow spanning inner-mid shelf. Diagenetic observed include micritisation, cementation, dissolution, replacement, physical chemical compaction, fracture filling calcite cement. represents deepening upward sequence below system tract highstand systems regressive could good reservoir characteristics, serve as an excellent rock, be primary target for future exploration.