Lithofacies and Ichnology of Jumara Formation of Bharasar Dome, Kachchh, Western India

Bharasar dome of the Charwar hill range, south of Bhuj, Kachchh, western India, exposes ~180 meter thick rocks of the Jumara Formation (Callovian to Oxfordian). The Jumara Formation comprises of clastic and nonclastic sediments from which six lithofacies are identified which include: Intercalated Calcareous Shale-Siltstone (ICSS), Limestone (L), Intraformational Conglomerate (IC), Massive Feldspathic Sandstone (MFS), Gray Shale (GS) and Oolitic Limestone (OL). The whole sequence is bioturbated frequently and consists of mono-dominant to diverse groups of ichnogenera. Total 24 ichnospecies of 17 ichnogenera were identified which represents wide range of behavioural activities; dominated by feeding structures (Fodinichnia). Maximum diversity and abundance of ichnogenera are found in Intercalated Calcareous Shale Siltstone lithofacies whereas Oolitic Limestone lithofacies consists of dominant ichnogenus, Zoophycos. Trace fossils are poorly developed in Limestone, Massive Feldspathic Sandstone and Intraformational Conglomerate lithofacies. Grey Shale lithofacies does not reveal any trace fossil species. Preservational aspects, behaviour and morphology of these trace fossils are interpreted and discussed to understand the depositional environment. The sedimentological characteristics and the associated trace fossils indicate shoreface to offshore environment of deposition for the Jumara Formation of the Bharasar dome.