Growth rate and life span of Eocene/Oligocene Nummulites tests: Inferences from Sr/Ca ratio

S. Sarangi, A. Sarkar, M. M. Sarin, S. K. Bhattacharya, M. Ebihara, A. K. Ray

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The problem of growth rate and life span of Nummulites foraminifers, attaining giant sizes during the Eocene, has been addressed by analysing their Sr/Ca ratio across the Eocene/ Oligocene Boundary (EOB) of Kutch, western India. The Eocene ratio (∼ 1) rapidly decreases during the Oligocene (∼ 0.5) and is coincident with the extinction of most of the Eocene Nummulites species, a rapid enrichment of δ18O and decrease in both test size and species diversity across the boundary. The high Sr/Ca ratio in Eocene foraminifers can be explained by their rapid growth under a favourable climatic condition. The climatic deterioration (e.g. δ18O cooling) across the boundary and during the early Oligocene possibly forced the Nummulites to adopt a slower growth rate (and stunted growth). The rapid growth of the Eocene Nummulites indicates that the giant sizes of these protists need not necessarily involve a large life span.

Original languageEnglish
Pages (from-to)264-269
Number of pages6
JournalTerra Nova
Volume13
Issue number4
DOIs
Publication statusPublished - 2001 Aug 1
Externally publishedYes

ASJC Scopus subject areas

  • Geology

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