THE SEDIMENTOLOGY OF THE SERIKAGNI FORMATION (LOWER MIOCENE) AT SINJAR MOUNTAIN AREA, NW IRAQ

A. Alani, A; Asma,; Y. Tamar-Agha, Mazin

	THE SEDIMENTOLOGY OF THE SERIKAGNI FORMATION (LOWER MIOCENE) AT SINJAR MOUNTAIN AREA, NW IRAQ
Iraqi Bulletin of Geology and Mining
Article 1, Volume 11, Issue 1, 2015, Pages 55-78
Authors
a A. Alani; ; Mazin Y. Tamar-Agha
Abstract
This study deals with establishing the depositional environments, mineralogy and diagenesis of the Serikagni Formation (lower Miocene) in northwest Iraq. Four sections are described and sampled from Sinjar Mountain region, the only exposure area. Mineralogical studies revealed that the major mineral is calcite with variable admixture of insoluble residues, which are mostly clay minerals and quartz. Subordinate dolomite and infrequent glauconite and pyrite are also recorded. The main clay minerals are kaolinite, palygorskite and illite with occasional smectite. Petrographic analyses reveal that the Serikagni Formation comprises mostly micrite and skeletal grains, represented by dominantly planktic foraminifera and subordinate benthic foraminifera and bioclasts. The main diagenetic processes that affected the studied rocks are bioturbation, dissolution, neomorphism, cementation (granular), replacement and mechanical compaction. Field description and laboratory confirmation reveal the existence of three lithogies namely, limestone, marly limestone and limey marl arranged as orbital cycles. Petrographic analysis revealed three microfacies namely, Planktic Foraminiferal Lime Mudstone, Planktic Foraminiferal Wackestone/ Packstone and Biolithoclastic Packstone. Facies analysis indicates that deposition has taken place in a basinal environment with hemipelagic character (deep shelf, toe-of-slope and slope). Turbidites of slumping origin is identified at Sinjar section.
Keywords
Serikagni Formation; Lower Miocene; Basinal environment; Turbidite; Orbital cycles; Iraq

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