Stratigraphical Position of Piran Limestone Unit in Piran Area, Erbil Governorate, Kurdistan Region, Iraq: Insights from Occurrence of Calcareous Nannofossils

Abstract

The Piran Limestone Unit in the Kani Rash in Piran Subdistrict was studied in order to determine the stratigraphical and palaeontological relationships. Based on the general geology and structural relations of the thrust units in the surroundings the most representative layers were selected. The total number of the collected samples is 10. The same number of the thin sections were prepared and analyzed under the microscope. Lithofacies and Biofacies assemblages were determined from thin sections by using Polarized Microscope. Relatively no complete work has been published on the stratigraphy, palaeontology, depositional environment, and age determination of the Piran Limestone in Iraq. The objective of this study is to determine the stratigraphical and palaeontological relationships in detail for this unit through detailed description of the selected section in terms of petrography, facies analysis and subdivisions of facies in Piran Subdistrict at Northeast of Erbil Governorate, Kurdistan Region, Iraq. This will be accomplished by determining and assigning relative age of Piran Limestone based on occurrence of fossil assemblages. In order to conclude that, the studies of the local stratigraphy, palaeogeography, and sedimentology will play a major role in the determination of depositional environment of the units along the considered section. The study tries to establish the sedimentologic characteristics and boundaries of the unit with both lower and upper contacts. on the occurrence of Fasciculithus tympaniformis sp., Heliolithus riedelii sp., Reticulofenestra sp., Prinsius sp., Sphenolithus anarrhopus sp., and Sphenolithus moriformis sp., the age of this unit was determined to be Middle Thanetian.