Foraminifera And Age Of The Araej Formation In The Dukhan Oil Field, Western Qatar Arabian Gulf

Abstract

The detailed examination of the three members of the Araej Formation (lower Araej, Uwainat and upper Araej) in four wells, in the Dukhan Field, led to the identification of 36 foraminiferal species. Of these, 29 species belong to the arenaceous Suborder Textulariina. This fauna enable to subdivide the Araej Formation into five zones. The lower three zones are: the Ammodiscus offa's Zone in the lower half of the lower Araej member, the Pfenderiaa trochoidea Zone in the upper half of the lower Araej Member and the lower part of the Uwainat Member and the Trocholina intermedia Zone in the upper part of the Uwainat Member. These zones are of Bathonian age. The upper Araej Member includes a lower barren interval and an upper Kurnubia jurassica Zone. The upper Araej Member is considered to be of Callovian age. The distribution of the genus Pfenderina is largely controlled by sedimentary facies. It seems that members of the Suborder Lagenina never occur with Pfenderina in Middle Jurassic sediments of the Middle East. A correlation between the established zones and their equivalents in the surrounding regions is attempted.