Planktonic foraminiferal distribution of the Late Cretaceous to late Paleocene deposits of the Bandar Abbas area (Zagros Belt, SW Iran): An update of the bio- and lithostratigraphic framework

Abstract

In this paper, we present a biostratigraphic study of the planktonic foraminiferal associations of the Gurpi Formation outcropping in the Bandar Abbas area of the Zagros Belt (SW Iran). Two stratigraphic sections, Kuh-e Khush and Kuh-e Khamir, were logged and sampled, and the identification of the planktonic foraminiferal assemblages has allowed the recognition of eight Cretaceous biozones, namely Dicarinella asymetrica Zone, Globotruncanita elevata-Globotruncana ventricosa Zone, Radotruncana calcarata Zone, Globotruncanella havanensis Zone, Radotruncana calcarata–Globotruncana aegyptiaca Zone, Globotruncana aegyptiaca-Gansserina gansseri Zone, Gansserina gansseri Zone and Contusotruncana contusa-Abathomphalus mayaroensis Zone. This planktonic foraminiferal zonal framework reveals a latest Coniacian to late Maastrichtian age for the deposits of the Gurpi Formation in the two studied sections. The Cenozoic Interval of the studied sections, represented by the Pabdeh Formation, is attributed to the P3–P6a integrated Zone in the Khush section and the P4c Subzone (Acarinina soldadoensis) in the Khamir section. The data show that the Gurpi Formation at the Khamir locality rests disconformably upon the shallow neritic facies of the Ilam Formation, while in the Khush section this formation disconformably overlies the shallow carbonates of the Sarvak Formation. In addition to the in situ biota, reworked microfossils, such as calpionellids, calcareous algae and benthic foraminifera from older Jurassic (Surmeh Formation) and Cretaceous formations (Surgah equivalent, Sarvak, Kazhdumi and Dariyan formations) are recorded within several stratigraphic levels of the Gurpi Formation.