Role of Cementing Material in the Diagenetic History of Bhander Limestone of Simariya Area in Panna District, Madhya Pradesh

Abstract

Petrological studies of Bhander Limestone of Simariya area in Panna District indicate that the limestone has sparry calcite cement. On the basis of fabric characteristics of spars, four types of sparry calcite cements are noticeable (1) Fibrous non-ferroan calcite cement (2) dog tooth fringe cement (3) syntaxial rim cement, and (4) Drusy mosaic cement. Microfacies indicates that the Bhander Limestone was first chemically precipitated as lime mud, which was disintegrated by wave action, carried and laid down as oomicrite and intramicrite. Fibrous cement, forming coating of allochemical grains, must have undergone syngenetic precompaction. Percolating waters dissolved the fibrous aragonite, and calcium carbonate so liberated formed the low-magnesian, non-ferroan dog tooth fringe cement into which the fibrous cement grades. These cements were formed due to the effect of circulating water in the pore filling under near surface intermittently emergent marine environment. After early diagenetic cementation and partial lithification, the Bhander limestone has undergone a shallow submergence, where pore water chemistry favoured precipitation of ferroan calcite as drusy mosaic cement in the moldic porosity created during dissolution. It is a second generation ferroan calcite cement, which precipitated in the reducing environment, which is also late diagenetic. Ferroan nature of micrite calcite also point out its formation in a reducing environment. Other diagenetic changes in the limestone include neomorphism, silicification and dolomitisation and compaction and pressure solution.