The Kurdistan (NW) segment of the Zagros fold‐thrust belt, located in the Kurdistan Region of NE Iraq, forms the external part of the Zagros orogen and is bounded by the Zagros suture to the NE. To the SW is the Arabian Plate into which the deformation front has migrated progressively, beginning in the Late Cretaceous and culminating in the Tertiary. Regional compression resulted in obduction of the Mawat ophiolites and emplacement of the Avroman and Qulqula nappes onto the continental margin, and the formation of the Kurdistan foreland basin. In this paper, structural, stratigraphic and palaeontological data together with new field observations are used to investigate the tectono‐stratigraphic evolution of this basin, and to study the propagation of the deformation front from the Zagros Imbricate Zone in the NE towards the Mesopotamian foredeep in the SW. Six unconformities within the Kurdistan foreland basin succession are recognized: Turonian (base‐AP9; 92 Ma); Danian (base‐AP10; 65 Ma); Paleocene–Eocene (intra‐AP10; 55 Ma); late Eocene (top‐AP10; 34 Ma); middle‐upper Miocene (a local unconformity; intra‐AP11; 12 Ma); and Pleistocene. These unconformities can be divided into two groups; obduction‐related (Turonian, Danian, and Paleocene‐Eocene); and collision‐related (late Eocene, middle‐upper Miocene, and Pleistocene). The geographical position of the unconformities is used to determine the rate of propagation of the deformation front, which is estimated at ca. 3 mm/yr. This is in agreement with previous studies which suggested a NW‐ward decrease in the propagation rate. The rate was most rapid (2.95 mm/yr) in the Low Zagros Fold‐Thrust Zone and slower (2.06 mm/yr) in the High Zagros Fold‐Thrust Zone. The more rapid propagation rate in the former area may be attributed to the presence there of the Miocene Lower Fars Formation which acted as a shallow décollement surface. Within the Zagros fold‐thrust belt, the intensity of deformation decreases towards the foreland (SW). Deformation in the High Zagros Fold‐Thrust Zone is characterized by thrust imbricates and high amplitude fault‐propagation folds at the surface separated by narrow synclines. However, the Low Zagros Fold‐Thrust Zone (Simply Folded Belt) is characterised by detachments and low amplitude fault propagation folds separated by broad synclines. In the foredeep area, folds are confined to the subsurface. Deeply buried Jurassic units, together with Upper Cretaceous – Paleocene siliciclastics, and the evaporite‐dominated Lower Fars Formation may have acted as décollement surfaces in the NW segment of the Zagros fold‐thrust belt, and controlled the structural geometry and evolution of the area.

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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.

The Kurdistan foreland basin (NE Iraq) was formed as a result of the ophiolite-radiolarites obduction of the Iranian plate on the Arabian Plate. Extensive fieldwork for the determination of nine facies associations has been integrated with the planktonic and large foraminifera and other macrofossils biostratigraphic data in order to identify the sequence stratigraphic framework of the studied (late Campanian-Maastrichtian) successions comprising the Shiranish, Tanjero and Aqra formations. The studied successions are identified sensu Vial et al. (Payton CE (ed) Seismic stratigraphy application to hydrocarbon exploration memoir of the American association of the petroleum geologists, Tulsa, vol 26, pp 49-62, 1977) concepts, as three third-order depositional systems, within one major second-order depositional system, which is bounded by a sequence boundary of type one at its base and top. The Late Campanian-Early Maastrichtian third order is bounded by a middle Campanian gap as a sequence of boundary type one. The rapid drowning starts with planktonic foraminiferal-rich mudstone which indicates pre-flysch facies associations within starved foreland basin conditions and maximum flooding surface (MFS175). The sea level fell by the Early Maastrichtian, as characterized by a sequence boundary of type SBT2. The distal, medial and proximal turbidites flysch facies of the Tanjero formations manifest the second third-order depositional system. This may indicate a progressive shallowing upwards and characterized by MFS 180, which is placed at the top of the last planktonic-rich shale parasequences. The last third order is represented by rudist (Hippurites)-dominated carbonate parasequences (Late Maastrichtian-Aqra formation). The aggradational stacking pattern of the rudist lithosomes indicates the last MFS 190 during the Maastrichtian greenhouse. The sequence boundary is of type one which separates the Palaeocene molasses of Swais Group from the Maastrichtian sequence in the imbricated zone, while in the high folded zone it is replaced by Kolosh siliciclastic (Palaeocene) due to migrations of the Kurdistan foreland basin depocentre towards south-west. The reactivation of the deep-seated transversal faults is in addition to the sea level changes with south-westwards migration of the Zagros deformations front controlling the late Campanian-Maastrichtian supersequences framework.

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