Volume 18, Issue 46 (4-2008)
Abstract
The Gurpi Formation, at the type section (NW of Masjed-Soleiman) and in Sabze-kuh (SW of Borujen) are lithologically subdivided into 8 and 11 units, respectively. The study of planktonic foraminifera resulted in recognition of 7 biozones in Lali area and 4 biozones in Sabzeh-kuh area. These biozones are compared to the most standard biozones defined in Tethysian domain. Biozones I (Globotruncanita elevata Zone), II (Globotruncana ventricosa Zone) and III (Globotruncanita calcarata Zone) suggest the Early, Middle and Late Campanian, respectively. Biozones IV (Globotruncanita stuarti Zone) and V (Globotruncana aegyptica zone) represent Late Campanian. Biozone VI (Gansserian gansseri Zone) show Late Campanian-Early Maastrichtian and biozone VII (Abathomphalus mayaroensis) indicates Late Maastrichtian. In Sabze-kuh area, due to the decrease in water depth in Maastrichtian, biozones V, VI and VII were not recognized. Changes in water depth during the Campanian and Maastrichtian had a very important role in the distribution of planktonic foraminifera. In the early Late Campanian and Late Maastrichtian with decreasing of water depth, the globular, unkeeled planktonic foraminifera dominates the fauna. In the Late Campanian and during the Early Maastrichtian with increasing of water depth, the keeled foraminifera forms a significant portion of the planktonic foraminifera.
