Keywords : Avroman

Stratigraphy and Lithology of the Avroman Formation (Triassic), North East Iraq

Kamal H. Karim

Iraqi National Journal of Earth Sciences, 2007, Volume 7, Issue 1, Pages 1-12

Stratigraphy and lithology of the Avroman Formation (Triassic) were studied in Iraq and Iran. The study introduced new documentations about stratigraphy, lithology, fossil content and environment of deposition. Stratigraphically, it is very difficult to study the formation due to intense deformation, imbrication and even thrusting. However, it overlain by Qulqula Radiolarite Formation and Merga Red Beds in Iraq and Iran respectively while the underlying formation is not known as the lower boundary is not exposed. Lithologically, the formation consists mainly of pure limestone and no dolomite and marly limestone as previously mentioned. Microfacies include; grainstone, packstone and wackestone with association of oncoids, pelets, oolith and bioclasts. The fossils are relatively rare (except stromatolite or oncoids) and include gastropods, pelecypod green algae, echinoderms and forams. Environmentally, the formation was deposited in shallow isolated platform which was characterized by agitating warm normal marine water.