TY - JOUR ID - TI - THE MID – MIOCENE CLIMATIC OPTIMUM (MMCO) MANIFESTATION IN IRAQ: CARBON AND OXYGEN ISOTOPES PROXIES AU - Arsalan A. Othman ارسلان احمد عثمان AU - Sa'ad Z. Al-Mashaikie AU - Mustafa A. Ali مصطفى اسعد علي PY - 2022 VL - 18 IS - 2 SP - 1 EP - 24 JO - Iraqi Bulletin of Geology and Mining مجلة الجيولوجيا والتعدين العراقية SN - 18114539 AB - The present paper deals with the variability of the primary isotopic composition of seawater in the shallow water zone. Sedimentary successions of middle Miocene outcropping in the eastern part of Iraq provide an excellent archive of the oxygen and carbon isotopes. We analyzed the δ13C and δ18O to investigate the relationship between the lithostratigraphic units and the deviation of the stable isotopes. The results show a significant relationship between the depositional energy changes and both δ13C and δ18O composition. That displays the details of oxygen isotope events (Mi‐events) and additional information about Mi 2 and 3 zones, reflecting significant changes in the glaciation period, which have minor steps (interglacial period). At the same time, carbon isotope maxima (CM‐events) reflect changes in organic carbon burial and refine the Monterey Excursion. Facies analysis revealed several microfacies could be distinguished, reflecting depositional environments including; supratidal and intertidal, lagoon, patch-reef, and open marine environments, matching with their isotopes storage differential, enhancing 13C and high rates of sedimentation in deeper facies. The stable isotopes (18O/16O and 13C/12C) provide an excellent archive of the Neogene (middle Miocene Transgression) 's paleoceanography for the Neo-Tethys. Oxygen and carbon isotopic stratigraphy for bulk rock were analyzed to distinguish Monterey Event and climate optima.

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