Bryozoan Fauna from the Ora Formation (Late Devonian-Early Carboniferous) Within Selected Sections, in the Kurdistan Region, North of Iraq

Le résumé fourni par la source

The Ora Formation in the northern part of Iraq constitutes a significant sedimentary archive of the Devonian–Carboniferous transition and is widely regarded as Famennian–Tournaisian in age. Despite its stratigraphic importance, the bryozoan content of this formation has remained insufficiently documented. The present study provides the first focused taxonomic investigation of bryozoans from the Ora Formation in the Ora and Nazdor sections, Duhok Governorate, northern Iraq, and assesses their systematic and biostratigraphic significance. The studied successions are composed of bryozoan-bearing carbonate interbeds alternating with shale, and the investigated material was analysed by field sampling and thin-section petrography under transmitted light. Bryozoans occur mainly in carbonate beds within the upper parts of the studied intervals and exhibit a variety of colony sizes, growth forms, and internal skeletal structures. The assemblage is moderately diverse and comprises more than ten taxa attributable mainly to the orders Trepostomata, Cryptostomata, Fenestrata, and Cystoporata, in addition to several forms retained in open nomenclature owing to preservational and sectional limitations. The identified taxa and their morphological affinities demonstrate close relationships with both Famennian and Tournaisian bryozoan fossils previously described from comparable extra-Iraqi successions. This confirms the importance of bryozoans as a reliable palaeontological tool for age assessment and regional correlation across the Late Devonian–Early Carboniferous interval. Accordingly, the present study establishes a new bryozoan-based taxonomic framework for the Ora Formation in the northern part of Iraq and provides a basis for future systematic, palaeoecological, biostratigraphic, and palaeobiogeographic investigations.

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