In this paper, the biostratigraphy and sequence stratigraphy of marine Paleogene deposits from the Kopet-Dagh basin (NE of Iran) are described. Particularly the absence of Morozovella genus is discussed. In addition, the Paleocene/Eocene boundary has been studied in detail using the record of planktonic and larger benthic foraminifera. This boundary is located probably within a thin red horizon (~10–15？cm) representing a paleosoil. Close to this boundary is located the base of the calcareous test dissolution interval, with the dominance of agglutinated benthic foraminifera and with a sudden decrease in the richness of benthic foraminiferal species. Biostratigraphic studies led to the identification of 33 genera of larger benthic foraminifera and 5 genera of planktonic foraminifera. Petrographical studies indicate that these sediments, consisting of four carbonate lithofacies (15 subfacies), may have been deposited on a shallow carbonate platform (ramp type). These lithofacies have been deposited in open marine, shoal, lagoon, and tidal flat environmental conditions. Sequence stratigraphic analysis led to the identification of four third-order depositional sequences. The interpreted sea-level curve in the Kopet-Dagh basin can be correlated with Paleocene-Eocene global curves, with a sea-level fall in the latest Paleocene, followed by a sea-level rise in the earliest Eocene. 1. Introduction Paleogene, as a climatically highly dynamic period, is connecting the ice-free world of the Cretaceous to the glacially dominated world of the Neogene [1]. An abrupt climate warming of 5 to 10 degrees at the Paleocene/Eocene boundary, known as the Paleocene-Eocene Thermal Maximum (PETM), occurred approximately 55.5？Ma ago [1]. It has been mainly linked to the catastrophic release of carbon from sea-floor methane hydrate reservoirs (e.g., [2]). Remarkable stable oxygen and carbon isotope excursions have been detected in Antarctic waters near the end of the Paleocene (~57.33？Ma ago), indicating rapid global warming and oceanographic changes that caused one of the largest deep-sea benthic extinction of the past 90 million years [3]. Despite the lots of studies focused on the Paleocene/Eocene boundary, yet little is known about it in shallow-water setting. During the early Paleogene, the morozovellids and acarininids were immensely successful shallow-dwelling groups. They were well-known surface dwellers within the tropical and subtropical latitudes. Morozovella and Acarinina had similar ecological preferences, occupying the warm, and shallow, mixed layer of the oceans.
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