TRACE FOSSILS FROM THE JURASSIC ROCKS OF GANGTA BET, EASTERN KACHCHH, WESTERN INDIA

摘要

The Jurassic rocks are well exposed in Gangta Bet of the Wagad region, Eastern Kachchh. The succession consists of thick arenaceous unit overlain by the calcareous sandstone-siltstone-shales and capped by the algal limestone. The Lower sandstone units are highly ferruginized, fractured, weathered and exposed in core of the Gangta Dome. The calcareous sandstone-siltstone units are marked by well-preserved trace fossils. Total 27 ichnospecies of 19 ichnogenera falling in five ethological categories are identified from the Gangta Bet. The recurrent pattern of the trace fossil assemblages exhibit bathymetric controls and display development of Cruziana-like ichnofacies characterizing subtidal conditions of depositional environment. The algal limestone band over the trace fossil horizon is interrupted by the ripple calcareous sandstone and characterized by Maya and Helenae Assemblage Zones of Early- Middle Oxfordian age.