Planktonic Foraminiferal Biostratigraphy of the Upper part of Balambo Formation (Lower-Upper Cretaceous) in Azmer Anticline, Northeastern Iraq

Abstract

The present work is a part of detailed study of biostratigraphy of Balambo Formation (Lower Upper Cretaceous) from Azmer anticline northeastern Iraq. Lithologically, the upper part of the studied section (Balambo Formation) consists of dark gray, reddish brown shale and marl intercalation with amonitic and marly limestone. Based on planktonic foraminifera, the studied section is divided into five main biozones and two subzones. It is correlated with collection of global regional and local previous biozones. These biozones led to conclude that the age of the upper part of Balambo Formation extends over the Latest Aptian to MiddleLate Cenomanian. Moreover, the identified biozones are from older (at bottom) to younger (at top): 5Rotalipora cushmani Taxon range Zone. 4Thalmanninella globotruncanoides Interval Zone. 3Biticinella breggiensis Interval Zon. Ticinella praeticinensis Interval Subzone. Pseudothalmanninella subticinensis Interval Subzone. 2Ticinella primula Interval Zone. 1Paraticinella eubejaouensis Taxon range Zone.