Sedimentary Structures of the Tertiary Rocks Around Tarakeshwar, District Surat, Gujarat and their Diagenetic Significance

Tertiary rocks are exposed around Tarakeshwar, Surat district, Gujarat. These are mainly Eocene sediments which are predominantly clastic and are overlain by carbonate sediments. Several interesting sedimentary structures are revealed by calcareous claystones associated with fossiliferous limestones; among them concretions, septarian nodules and imatra stones are striking. These secondary sedimentary structures are developed due to chemical changes effected during diagenesis of the fine grained detrital sediments, probably involving precipitation of calcium carbonate in the pores of silt beds. The sediments were deposited in a near-shore environment of a shallow Eocene sea.