AMMONITE ZONATION OF THE JURASSIC ROCKS OF THE GANGTA BET AREA, WAGAD REGION, EASTERN KACHCHH, INDIA

摘要

Gangta Bet, a structurally controlled elliptical dome, occurs as small detached landmass situated on the western fringe of Wagad highland and comprises thick marine clastic and non-clastic sequence of the Upper-Middle Jurassic period. It comprises 103 meter thick exposed sequence, which consists of various types of sandstones, shale, conglomerate, and limestone. Top part of the sequence is composed of abundant ammonitic fauna; the intercalated calcareous sandstone-shale consists of Peltoceras athleta, Peltoceratoides semirugosum; the Gangta ammonite band, a limestone unit, occurs near the top of the sequence as an important marker horizon and consists of Mayaites (mayaites) maya, Mayaites sp. Perisphinctes (Arisphinctes) helenae, Perisphinctes (kranosphinctes) kranaus Perisphinctes (Dichotomosphinctes) and Perisphinctes sp., belonging to super family Stephanocerataceae and Perisphinctaceae. The ammonite species of Gangta Bet display three Biozones and five subzones which indicate that the age of the Gangta Bet rocks ranges from Late Callovian to Early Middle Oxfordian.