Keywords : Qulqula Conglomerate
Iraqi National Journal of Earth Sciences,
2007, Volume 7, Issue 1, Pages 55-68
Previous studies considered Qulqula Conglomerate Formation and Qulqula Radiolarian Formation as two units that comprise Qulqula Group. They mentioned that the former formation overlies the later gradationally. The type sections of both formations occur at Kulkula Gorge, about 25 km to the northeast of Ranyia Town. These studies indicated the age Qulqula Conglomerate Formation as Albian-Cenomanian and referred to deposition in deep basin of high tectonic activity. This tectonic is punctuated by deposition of the wildflysch which is represented by 1200 m of conglomerate, sandstone and shale.
However, during restudy of the lithology, stratigraphy and facies of Qulqula Conglomerate Formation at type section, any of the above characteristics are not observed. Conversely, many new data are recorded for the first time that revised lithology; stratigraphic position and age of the formation as concerned to previous ones. As it is shown the lithology of the formation is similar to the lithology of unit three of the Red Bed Series. This is proved by the following lines of evidence: Lateral tracing of the formation to the type locality of the Red Bed Series (Suwais village), indicating of their mergence with each other in a depositional condition near the village. Several species of Alveolina and Nummulite large forams are found in the gravels and boulders of the formation at the type locality. The age of these forams are Eocene; therefore the age of Qulqula Conglomerate Formation is changed to yonger than Eocene. The wildflysch facies as cited before is nothing except the molasse of Red Bed Series as it contains same alternation of lensoidal conglomerate and sandstone with some shale and claystone. This study suggests modification stratigraphical position of the formation in the type area so that it must be included in the Red Bed Series and Qulqulq Conglomerate Formation must be abandoned.