Biozonation of the Uttatur Group, Trichinopoly, Cauvery Basin

Twenty-five species of planktonic foraminifera are identified from the marine sedimentary formations of the Uttatur Group cropping out in Trichinopoly area of the Cauvery Basin. Five zonal subdivisions are proposed for the Uttatur Group on the basis of local planktonic forminiferal sequences. These zones range in age from Albian to Early Turonian. The proposed zones are: Hedbergella planispira assemblage zone and Planomalina buxtorfi Range zone for Albian; Rotalipora evoluta Range Zone and Rotalipora reicheli Range zone for Cenomanian and Marginotruncana helvetica - M. sigali Assemblage zone for Turonian. A correlation between the Uttatur Group and its coeval in Trinidad, North America, Southern Europe and North Africa is attempted in terms of the established planktonic foraminiferal zones.