The Bade Section (Dohuk Area, Northwest Iraq): A Reference Record for the K-Pg Boundary on the Arabian Plate

A high-resolution biostratigraphic analysis based on planktonic foraminifera at the Bade section (Dohuk area, northwest Iraq) across the K-Pg boundary shows an uninterrupted pelagic succession. The succession consists of the uppermost part of the bluish marlstone of the Shiranish Formation (Maastrichtian), and the buff brown shaley marlstone of the Aaliji Formation (Danian in age). The planktonic foraminiferal data reveal the occurrence of three (CF3, CF2, CF1) Cretaceous biozones for the uppermost Maastrichtian stage, and six (P0, Pa, P1a, P1b, P1c, P2) Paleogene biozones for the Danian stage. Chemostratigraphic analyses along with XRD of the primary mineralogy including the clay mineral assemblages, and field gamma-ray spectrometry fully support the interpretation of the biostratigraphic data, the identification of the K-Pg transition of the Bade section, and its link to the globally recognized meteorite impact of the Chicxulub crater (Yucatán Peninsula, Gulf of Mexico). The 4 mm-thick KPg boundary layer is a rusty-looking, yellowish red, discontinuous, and laminated, horizon. This layer is rich in impact ejecta of iron spherules, deformed quartz grains, and goethite and coesite minerals. A consistent drop of CaCO3 and the radiometric peak of the total gamma-ray radiation across the boundary zone correspond to the globally documented profiles of the K-Pg boundary zone at many global localities. These are important diagnostic features of the globally recognized meteorite impact material, with which, the Bade section is correlated to the “distal” localities of the K-Pg sections worldwide. The complete, well preserved, and unique features of the K-Pg transition at the Bade section support considering it as a reference section for the K-Pg boundary in the Arabian plate.