GENESIS OF LIMESTONE-MARL ALTERNATIONS IN CARBONATE SEQUENCE OF EOCENE SALT RANGE POTWAR PLATEAU, PAKISTAN

Abstract

The thesis focus on the genesis of limestone marl alternations in the Carbonates sequence of the Eocene Salt Range-Potowar Plateau in Pakistan. Three sections were studied: the Nammal Dam section, the Chal Abdal section, and the Tatryal-Sethi section. The study used microfacies analysis of limestone and SEM images of marl and limestone samples. This research investigated the processes responsible for forming alternations in carbonate sequences. The study analyses twenty-four thin sections of limestone samples under the microscope. Four samples of limestone marl alternations are studied using a scanning electron microscope. The study results show that cementation, dissolution and neomorphism significantly formed limestone marl alternations. The alternations were formed due to differential diagenesis in a shallow marine environment. The SEM images revealed that the limestone samples were characterized by a high concentration of micrite, microspar cementation, and altered nano fossils, indicating early cementation and compaction in marl; well-preserved fossils refer to lithification in limestone samples. On the other hand, the marl samples showed evidence of dissolution and neomorphism, resulting in the formation of fine-grained sediments. The complex reciprocity of diagenetic processes responsible for the formation of alternations in Eocene carbonates of the Salt Range emphasizes the importance of differential diagenesis in the formation of limestone marl alternation