الملخص

Stratigraphic units during Lower Cretaceous in southern of Iraq were affected largely by tectonic agent. Neo-Tethys ocean occupied the distance between passive margins of Arabian and Iranian plates. South of Iraq represented the continental shelf of passive margin of Arabian plate. This tectonic situation made the sediments in eastern parts of passive margin in south of Iraq effected by marine agents, and the sediments in western parts was effected by continental agents, whereas the middle parts was effected by both agents. As result of that, three sediment regions were formed in south of Iraq. First, marine sediment region that occupy the eastern part of south of Iraq near the Iraq-Iran borders. Second, mixed sediment region that occupy Basra area and extend toward north. Third, continental sediment region that occupy western part of Basra near the western desert. Half graben basins that formed by listric faults in the passive margin caused the local changes in distribution of sediments in south of Basra. These three sediment regions formed all during Lower Cretaceous and maybe extend toward the middle of Iraq and north of Baghdad