Biostratigraphic analysis of the K/Pg boundary using calcareous Nannofossil from Sulaimani area, Kurdistan Region, Iraq

摘要

The Cretaceous/Paleogene boundary in the Kurdistan region of Iraq in general is still debatable, however examination of the boundary at the Qalbaza and Dartw localities in the Sulaimani area of the Kurdistan Region show different results regarding the biostratigraphy of the boundary zone. In the current study, the calcareous nannofossil assemblages and biostratigraphy across the K/Pg boundary in Sulaimani area of Kurdistan were focused. The rock strata in the study sections are characterized by alternations of organic shale, siltstone, fine- grained sandstone, gravel and organic limestone interlayers within the Tanjero Formation (Late Maastrichtian) and the overlying Kolosh Formation (Paleocene- early Eocene). The boundary is biostratigraphically delineated by the first occurrences of Biantholithus sparsus, Cruciplacolithus spp. and Coccolithus pelagicus. Additional important biostratigraphic marker is plus an acme of Thoracosphaera operculata of biozone NP1 above biozone CC26 which is generally consisted of Micula murus, Micula Prinsii and Lithraphidites quadratus. This biostratigraphic analysis indicates no hiatus, although it shows reworked Cretaceous taxa are recorded above the K/Pg boundary within zones NP1 and NP2.