he Upper Cretaceous Kometan and Shiranish formations of the Kurdistan region, NE Iraq, yield diverse planktonic foraminiferal assemblages, with a total of 93 species, which enable recognition of nine biozones and two subzones spanning the early Turonian to late early Maastrichtian. Sequential changes in planktonic foraminiferal assemblages map discrete intervals within the Kometan and Shiranish formations that suggest dominantly warm, nutrient-poor marine surface and near-surface conditions during the mid-Turonian to late Coniacian, latest Santonian, and late Campanian, and cooler more nutrient-rich surface and near-surface waters in the early Turonian, early to late Santonian, early Campanian and early Maastrichtian. These intervals appear to correlate with changes in water masses from other regions of the Cretaceous palaeotropics, and with a phase of global, early Maastrichtian climate cooling. The major intra-Campanian truncation surface between the Kometan and Shiranish formations, recognized from the foraminiferal biostratigraphy, represents a lowstand that appears to equate with regional tectonics and ophiolite obduction across the NE margin of the Arabian Plate.

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Species of the benthonic foraminiferal genus Bolivinoides provide a refined biostratigraphic biozonation for the Late Campanian to Early Maastrichtian (Late Cretaceous) Shiranish Formation in NE Iraq. Three biozones and two subzones are identified: the Bolivinoides decoratus Biozone (Late Campanian) subdivided into a lower B. decoratus Subzone and upper B. laevigatus Subzone; the B. miliaris Biozone (Earliest Maastrichtian); and the B. draco Biozone (late Early Maastrichtian). These zones can be related to the biostratigraphical interval of the Globotruncana aegyptiaca (Late Campanian), Gansserina gansseri (latest Campanian–Early Maastrichtian) and Contusotruncana contusa (late Early Maastrichtian) planktonic foraminiferal biozones. Combined, the benthonic and planktonic foraminiferal biostratigraphy enables the informal recognition of lower and upper intervals within both the Globotruncana aegyptiaca and Gansserina gansseri biozones that may be important for more refined inter-regional correlation in the Middle East and North Africa. The new Bolivinoides biozonation precisely locates the Campanian–Maastrichtian boundary in NE Iraq. The foraminiferal assemblages also constrain the timing of a shallowing marine trend in the Shiranish Formation beginning from the latest Campanian that is consistent with shallowing facies noted globally at this time.