Abstract
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.
Highlights
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]
This study explores the biostratigraphy and sequence stratigraphy of the Chehel-Kaman Formation in central Kopet-Dagh basin using planktonic, agglutinated, and larger benthic foraminifera. larger benthic foraminifera (LBF) are major components of many Paleogene carbonate platforms around the world in Paratethys realm
Petrographical studies indicate that these sediments may have been deposited in open marine, shoal, lagoon, and tidal flat environments within a shallow carbonate ramp depositional system
Summary
As a climatically highly dynamic period, is connecting the ice-free world of the Cretaceous to the glacially dominated world of the Neogene [1]. 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. The presence of Morozovella genus depends on climatic, marine currents and facies changes It depends on sedimentation and diagenetic processes. Larger benthic foraminifera (LBF) are major components of many Paleogene carbonate platforms around the world in Paratethys realm. They are photosymbiotic organisms and lived in warm, oligotrophic, and shallow waters within the photic zone. Many works have been focused on Paleocene/Eocene boundary, but preboundary sediments (Late Paleocene) still needs to be studied more in detail especially in shallow-water settings
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