Maastrichtian Planktic Foraminiferal PaleoecologyWithin the Tanjero Formation, Sulaymaniyah City, Kurdistan Region, Northeastern Iraq.

This study focuses on planktic foraminifera to interpret the paleoecology and paleogeography of the uppermost 20 m of the Tanjero Formation below the Cretaceous/Paleogene (K/Pg) boundary of the Kurdistan Region, northeastern Iraq. In the lower part of the studied section, which was deposited in deep water (more than 100 m), the planktic foraminifera species with doublekeeled tests Abathomphalus, Marginotruncana, Globotruncana, Gansserina, and Rugotruncana (Morphotype 3), are predominant. The middle part of the section is characterized by abundant species from the Globotruncanella and Globotruncanita genera, which have a single-keeled test, representing deposition in intermediate water (50-100 m depth) (Morphotype 2). The upper part of the section is marked by an abundance of genera with a nonkeeled test, including Hedbergella, Heterohelix, Pseudoguembelina, Pseudotextularia, Guembelitria, Planoheterohelix, Rugoglobigerina, Globigerinelloids Plummerita, and Rugotruncana, which are indicators of shallower water (approximately 50 m depth) (Morphotype 1). The diverse planktic foraminifera genera in this section are typical of Tethyan provinces, suggesting a stable, mesotrophic environment. The planktic foraminiferal assemblage from the uppermost part of the formation suggests paleoceanographic conditions that favored opportunistic organisms. This is evidenced by the presence of the genus Pseudoguembelina, a successful surface and subsurface dweller in tropical and subtropical open oceans with warm and oligotrophic surface waters. The expansion of this strongly photosymbiotic genus is attributed to favorable palaeoecological conditions in the Late Cretaceous oceans. The results obtained imply the presence of a well-stratified water column, a tropical to subtropical climate, and deposition in the outer shelf to upper bathyal environments. These conditions account for the presence of well-preserved and highly diversified Maastrichtian foraminifer assemblages of the globotruncanid species, which include: Hedbergella, Praeglobotruncana, Marginotruncana, Globotruncana, Contusotruncan, Globotruncanita, Archaeoglobigerina, Rugoglobigerina, Rugotruncana, Globotruncanella, Gansserina, and Abathomphalus. [ABSTRACT FROM AUTHOR]