Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

N. Rajagopalan ¹

Affiliations
1 Department of Geology, Annamalai University, Annamalai Nagar, IN

Abstract

The early Tertiary sediments of Pondicherry, South India, have yielded a new Ostracode fauna. A new genus, Neocytheridea (type species: Neocytheridea inflata Rajagopalan) and six new species are described: Hermanites pondicherriensis, Actinocythereis indica, Cythereis anastomosa, Cythereis tamulicus, Schizocythere? Levinsoni and Neocytheridea inflata.

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N. Rajagopalan ¹

Affiliations
1 Department of Geology, Annamalai University, Annamalai Nagar, IN

Abstract

Three formal lithological units namely the Valudavur, Mettuveli, and Pondicherry formations have been recognised in the Cretaceous-Lower Tertiary rocks of Pondicherry, South India. The Pondicherry formation is divisible into four informal units viz: the lower marlstone, the algal limestone, the discocyclinid limestone and the upper marlstone. The three formations are defined. A detailed foraminiferal study of these units has shown that the Valudavur and Mettuveli formations are of late Cretaceous age and contain the Globotruncana lapparenti tricarinata and the Globotruncana gansseri assemblage zones. The existence of latest Maestrichtian strata in this area is doubtful. The Pondicherry formation is of Paleocene-Early Eocene age and contains all the planktonic foraminiferal zones established in Trinidad B. W. I. The Cretaceous-Tertiary boundary is clearly definable in terms of the planktonic fauna. Results of a paleoecologic study of the sediments are presented. It appears that the Cretaceous-Early Tertiary sedimentation in the Pondicherry area took place under mid to outer neritic conditions.

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