Iraqi National Journal of Earth Science

Fundamentally, the current study is concerned with the investigation and diagnosing of Ostracoda fossils from the subsurface section of the Hartha Formation (Late Campanian - Early Maastrichtian) from (Ba-8) well at central Iraq. Fifty-nine Ostracoda species belonging to (29) genera/ subgenera from (13) families are diagnosed and classified to their ranks according to the standard systematic paleontology. Whereat (57) species are attributed to species previously described from local and regional studies. Two species are left under open zoological nomenclature basically because of lack of specimens. As a result, the study inferred that the species diagnosed in the Hartha Formation belong to the Late Campanian - Early Maastricht. As These species are very similar in terms of the external appearance and geologic age to the same species that were compared with them and which were previously described in the regions of East, West, and North Africa as well as the Arabian Gulf region.

Ostracode biostratigaphy were investigated in detail from three formations (Shiranish, Hartha and Mushorah ) in subsurface sections of four boreholes Northwest and centre of Iraq.
On the basis of the ostracode species distribution, the studied formations were divided into four ostracode biozones as follows:

Biozone 1: Cytherella IRC 22 Interval zone. (Early Campanian).
Biozone 2: Occultocythereis elongata Interval zone. (Late Campanian).
Biozone 3: Krithe sp. M 1113 Interval zone. (Early Maastrichtian).
Biozone 4: Holcopocythere bassiporosa Interval zone. (Late Maastrichtian).

Depending on the above biozones correlated with other previous works from Iraq and the Middle East regions the following ages were proposed for the studied formations:

Shiranish Formation: Late Campanian - Maastrichtian.
Hartha Formation: Late Campanian - Early Maastrichtian.
Mushorah Formation: Early Campanian.