The effect of the paleoclimatic and paleoenvironmental changes on the structure of the biotic communities are stronger and better recorded in the shelf area than in the open sea. The present study is devoted to impact of climatic events on some species of calcareous nannofossils. For this reason, 17 samples of surface sediments of the Persian Gulf were studied. Preservation of calcareous nannofossils in surface sediment samples was good and the dominant species were Gephyrocapsa oceanica, Emiliania huxleyi, Helicosphaera carteri and Calcidiscus leptoporus. The presence of these taxa indicated the Holocene sediments in the study area were deposited in the warm water and the Persian Gulf was a shallow and hyposaline basin in which productivity of calcareous nannofossils was high

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