Upper Cretaceous planktic foraminiferal from the Zagros basin (north-northwest Shiraz), Iran

Abstract

The litho-and biostratigraphy of Upper Cretaceous (Gurpi Formation) has been investigated within a well-exposed section at the northern limb of Pey zard anticline, Abnow area, Southern Iran. The studied section consists mainly of grey marl, calcareous pyritic shale, and argillaceous limestones. The Formation unconformably overlies Sarvak Formation and the Tarbur Formation overlies it unconformably. The samples of the section under investigation yielded rich and various planktic foraminiferal taxa, where forty planktic species belonging to eighteen genera have been recognized, the detailed foraminiferal investigation permits the recognition of the most standard biozones defined in Mediterranean regions, especially Tethyan domain. Depending on the stratigraphic distribution and relative abundance of planktic foraminiferal faunas, the studied section is subdivided into eleven biozones, which confirm a Campanian- Maastrichtian age of the Gurpi Formation. Biozones 11 (<em>Globotruncanita</em> <em>elevata </em>zone), 10 (<em>Globotruncana ventricosa </em>zone) and 9 (<em>Globotruncanita calcarata </em>zone), 8 (<em>Globotruncanella havanensis</em> zone), 7 (<em>Globotruncana aegyptiaca </em>zone) represent the Early, Middle and Late Campanian, respectively.<em> </em>Biozone 6 (<em>Gansserina gansseri</em> zone) represent Late Campanian- Early Maastrichtian, Biozones 5 (<em>Contusotruncana contusa</em>/<em>Racemiguembelina fructicosa</em> zone), 4 (<em>Abathomphalus mayaroensis</em> zone), 3 (<em>Pseudoguemblina hariaensis</em> zone), 2 (<em>Pseudoguemblina palpebra</em> zone), 1 (<em>Plummerita hantkeninoides</em> zone) suggest the Early- Late Maastrichtian, respectively.