Carbonate Microfacies Analysis of Sinjar Formation from Qara Dagh Mountains, South–West of Sulaimani City, Kurdistan Region, Iraq

Abstract

The paper describes the carbonate microfacies identified in the Sinjar Formation (Late Paleocene-Early Eocene) cropping out in Qara Dagh Mountain, near Sulekan Village approximately 20km south-west of Sulaimani (Iraq). One section (62m thick) has been measured in the field and closely sampled to undertake detailed microfaciesal and micropalaeontological studies to determine the formation's age and environment of deposition. A number of 93 samples were collected illustrating all the lithological changes along the section. The limestone in the studied area is hard and extremely rich in large foraminifers (soritids, rotaliids, nummulites, miliolids) and green algae (dasycladales). The investigation of the thin sections allowed us to identify the carbonate microfacies (18 types and subtypes) and the micropaleontological association (foraminifers and green algae), to determine the age of formation and to reconstruct the paleoenvironment of deposition (fore-reef, reef, back-reef). Based on the field observations and the studied thin sections, we determined three Units of a carbonate platform (I, II and III) from the base to the top of the section: Unit I with coralgal associations, Unit II is dominated by larger foraminifers and characterized by the absence of coralgal associations, while Unit III is dominated by small foraminifers (mostly miliolids), peloids and green algae. It is partially dolomitized.