Sequence Stratigraphy of the Lower Jurassic Formations in Key Hole, 5/4 - Western Iraq

Abstract

The Lower Jurassic Silisiclastic – Carbonate Succession of Western Iraq is represented by Ubaid, Hussinyiat and Amij formations. It was subdivided into several microfacies that are distinguished on the basis of their depositional texture. Five distinct depositional setting were recognized: fluvial, restricted marine, shallow open marine, inner barrier and Shoal. Based on microfacies and sequence stratigraphic study, five third order sequences in K.H.5/4 were identified. These cycles were divided into eight asymmetrical fourth orders, their asymmetry reflect the imbalance between the rate of sea level fluctuations and rate of subsidence and low sediment influx.