Foraminiferal composition and age of the Chari Formation, Jumara Dome, Kutch

摘要

The Chari Formation exposed at Jumara Dome, western Kutch yielded a prolific foraminiferal assemblage comprising 51 species, including one new species. Sixteen species are reported for the first time from the Indian region. The foraminiferal assemblage, dominated by families Vaginulinidae and Nodosariidae, is employed to date these sediments. The assemblage includes mostly long-ranging species. However, on the basis of a few short-ranging species restricted within the Callovian-Oxfordian and some species though long-ranging but mostly occurring in the Callovian-Oxfrodian sequences of different parts of the world, a Callovian to Oxfordian age is assigned to the studied sequence. A Callovian age is favoured as the lower limit of the Chari Formationof the Kutch Jurassic on the basis of some representative Callovian foraminiferal species occurring in the lowermost lithounit of the Chari Formation in the Jumara Dome. An attempt is made to delineate the Callovian-Oxfordian boundary in the studied sequence on the basis of some fairly restricted and characteristic Callovian and Oxfordian foraminiferal species.