Lithostratigraphy and Environmental Considerations of Cenomanian-Early Turonian Shelf Carbonates (Rumaila and Mishrif Formations) of Mesopotamian Basin, Middle and Southern Iraq

Govand H. M. Sherwani, Adnan A. M. Aqrawi

Rumaila and Mishrif Formations form the major part of the Cenomanian early Turonian deposits of middle and southern Iraq. The Rumaila Formation consists of lithographic chalky limestone at the lower part and marly limestone and marl at the upper part. The formation represents deep off-shelf deposits, whereas the overlying Mishrif Formation is composed of various types of shallow-shelf carbonates such as rudist-bearing patchy reefs and lagoonal and off-shelf limestones.

An environmental model is suggested to delineate the stratigraphic relationships between the above mentioned two formations and to correlate them with their equivalents in central Iraq (i.e., Mahilban, Fahad, and Maotsi Formations). The gradational contact between the two formations and the intertonguing with their equivalents are considered to be the most important stratigraphic phenomena.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.