New Biostratigraphic Ideas About the Cretaceous / Paleogene Boundary from Selected Sections in Kurdistan -Mesopotamian Foreland Basin, Northern Iraq

Abstract

A composite biostratigraphic study has been carried out from four selected sections representing an interval between the Cretaceous/Paleogene (K/Pg) boundary within the Imbricated Zone (Chwarta – Mawat ), Sulaimani area, Kurdistan region northern Iraq. The study covers the Maastrichtian successions, represented by the upper part of the Tanjero and Aqra formations, and the Paleogene succession, represented by the lowermost portion of the Suwais Group. The biostratigraphic study is based on the Large Benthic Foraminifera, supported by planktic foraminifera, Calcareous Nannofossil biozone, and ammonite biozones, which are in turn compared with the local and international biozones. The recorded large benthic foraminifera biozones are: - Loftusia minor, Loftusia coxi, Orbitoides media, and Lepidorbitoides socialis Assemblages Zone(indicates early Late Maastrichtian age).Loftusia morgani, Siderolite calcitrapoides, Orbitoides apiculatus Assemblage Zone (indicates middle Late Maastrichtian age). Loftusia persica-Loftusia elongata Assemblage Zone (indicates late Late Maastrichtian age). The Pseudoguembelina hariaensis Partial Range Zone (CF3) recorded in Kato and Maukaba sections shows an middle Late Maastrichtian age. The recorded Calcareous Nannofossils are related to the Micula murus-Micula prinsii (CC26) Assemblage biozone recorded for the first time in the studied area and almost of Late Maastrichtian age but not extend to the latest Maastrichtian. Also, for the first time, an ammonites biozone was recorded in this area and represented by Hoploscaphites constrictus crassus Partial Range Zone (indicates Early Late Maastrichtian). As a result, the K/Pg represents a significant gap (about 5my) and unconformity with 500m conglomerates.