Sequence stratigraphy of the Qom Formation in the Sirjan–Abadeh region

Sequence stratigraphy of the Qom Formation deposits (in two stratigraphic sections) in the Sirjan–Abadeh region has been studied. This formation in the Sirjan area (Bujan section; with Rupelian–Chattian age and 156 m thickness), consists mainly of medium- to thick-bedded and massive limestones and marls. They are unconformably underlain by the polygenetic conglomerate with indeterminate age, and unconformably overlain by the quaternary alluvium. The Qom Formation outcrops in northern Abadeh (with Rupelian–Chattian age and 85 m thickness) consist mainly of massive and bedded limestones, shales, and conglomerates. They are conformably underlain by the Lower Red Formation and unconformably overlain by the quaternary alluvium. Eleven different microfacies, belonging to open marine (middle ramp), lagoon (inner ramp), beach, and braided streams were recognized. Based on the field investigations, deepening and shallowing patterns in microfacies, stacking patterns, and the distribution of foraminifers, four third-order depositional sequences in the Bujan section and five third-order depositional sequences in the Abadeh section have been identified. These depositional sequences are bounded by both type 1 and 2 sequence boundaries. Sequence boundaries are mainly characterized by the abrupt change in lithology and biotic components.