Abstract

Orbitoides is a large size benthic foraminifera of Tarbur Foarmation (Late Campanian -Maastrichtian) distributed from Northwest to southeast of Zagros area. From the Paleoenvironment point of view this genus lives in shallow environment with high aggitation, high light penetration and low clastic particles in let (like reefs and barrier reefs). The Paleogeographic distribution of Orbitoides is between 28̊ 35´ and 34̊ 18´ Northern latitude. The number and variety of the genus decrease from southeast to Northwest of the area and is accordance with temperature reduction toward northern parts and hyaline wall of them. Studies show that the abundance of Orbitoides depends on temperature, type of existing sediments and local tectonic which affects the depth sub-basins.

Keywords: Orbitoides; Tarbur formation; Zagros; Paleogeography