Middle Jurassic Trace Fossils from Habo Dome, Mainland Kachchh, Western India

Middle Jurassic rocks of the Habo Dome consist of well-preserved abundant trace fossil genera. These are described from the black limestone of Jhuno Formation and overlying thick classic sequence which is capped by thin bands of oolitic limestone of Jumara Formation. Total 30 ichnospecies of 23 ichnogenera are identified and their preservational aspects, ecological observations, producers and behavioural aspects are discussed. The trace fossils are found in subtidal sequences i.e. sandstone-siltstone-shale partings, thick, massive and cross-Bedded sandstones and in shelf sequences i.e. black limestone which consists of abundant Chondrites species with resting traces (Lockeia). The clastic sequence exhibits poorly sorted and intensely bioturbated cross-bedded sandstone, ripple-marked ferruginous sandstone and laminated shale-siltstone lithofacies which consist of three dimensional buiTow systems of Ophiomorpha, Thalassinoides and Spongeliomorpha, feeding burrows (Rhizocoralhum, Chondrites, Halymenidium, Gordia, Rutichnus, Planobtes) and crawling traces (Scolicia, Gyrochorte) Massive sandstone facies is moderately bioturbated while shale, conglomerate, shell bed and oolitic limestone lithofacies are poorly bioturbated (Thalassinoides). Wave and current energy, substrate consistency, food supply and bathymetry may have influenced the distribution of trace fossils m the shallow marine environments of the Middle Jurassic rocks of the Habo Dome.