An integrated study of upper Campanian-lower Maastrichtian carbon isotopes and calcareous plankton biostratigraphy of the Kurdistan Region,northeastern Iraq |
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| Institution: | 1. Exploration Department, Egyptian Petroleum Research Institute, Nasr City, 11727, Egypt;2. Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen C., Denmark;3. Department of General Sciences, College of Education and Natural Sciences, Charmo University, 46023, Chamchamal, Sulaimani, Kurdistan region, Iraq;4. Geology Department, Faculty of Science, Tanta University, Egypt;5. Faculty of Natural Resources and Environment, Department of Earth and Environmental Sciences, The Hashemite University, Jordan;6. National Research Institute of Astronomy and Geophysics, Egypt;1. Faculty of Geography and Biology, Pedagogical University of Cracow, Podchor??ych St. 2a, Kraków 30-084, Poland;2. Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Aleje Mickiewicza 30, Kraków 30-059, Poland;1. Geological Institute, ETH Zurich, Sonneggstrasse 5, 8092 Zuerich, Switzerland;2. Paleontological Institute, University of Zurich, Karl Schmid-Strasse 4, 8006 Zuerich, Switzerland;1. Departamento de Estratigrafía y Paleontología, Universidad de Granada, Avda. Fuentenueva s/n, 18002, Granada, Spain;2. Instituto Andaluz de Ciencias de la Tierra, Consejo Superior de Investigaciones Científicas-Universidad de Granada, Avda. de las Palmeras n 4, 18100, Armilla, Granada, Spain;3. Dipartimento di Fisica e Geologia, via Pascoli snc, 06123, Perugia, Italy;1. National Institute of Marine Geology and Geoecology Bucharest, 23-25 Dimitrie Onciul, RO-024053 Bucharest, Romania;2. University of Bucharest, Faculty of Geology and Geophysics, 1 Nicolae B?lcescu Avenue, RO-010041 Bucharest, Romania;1. Université de Lorraine, UMR CNRS 7359 GeoRessources, BP 70239, F-54506 Vandoeuvre-lès-Nancy, France;2. 6D avenue Général de Gaulle, F-05100 Briançon, France (retired from Université Lyon 1);3. Université Lyon 1, Laboratoire de Géologie de Lyon, CNRS UMR 5276 & Institut Universitaire de France, 2 rue Raphael Dubois, Campus La Doua, F-69622 Villeurbanne cedex, France;4. Sorbonne Universités, UPMC Univ Paris 06, UMR 7207 (CR2P), MNHN – UPMC – CNRS, Tour 46-56, 5ème, case 104, 4, place Jussieu, F-75005, Paris, France;1. Department of Earth Science, Graduate School of Science, Tohoku University, Aramaki Aza Aoba 6-3, Aoba-ku, Sendai 980-8578, Japan;2. The Center for Academic Resources and Archives, Tohoku University Museum, Tohoku University, Aramaki Aza Aoba 6-3, Aoba-ku, Sendai 980-8578, Japan;3. Faculty of Science, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan;4. Earthquake Research Institute, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan;5. Department of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Chikusa, Nagoya 464-8601, Japan;6. Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Natsushima-cho 2-15, Yokosuka 237-0061, Japan |
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| Abstract: | New carbon (δ13C) isotope records calibrated by planktonic bioevents provide general support for a late Campanian age assignment of the Shiranish Formation (Fm.) and its boundaries in the Dokan section (NE Iraq). The Shiranish Fm. is characterised at the base by a mid-Campanian unconformity as can be interpreted by absences of nannofossil zones CC20-21. The Shiranish Fm. then spans nannofossil biozones CC22-CC23a (UC15d-eTP to UC16aTP). Results obtained on carbon isotopes suggest that diagenesis affected and compromised a few carbonate samples in the uppermost 50 m of the section. However, once these samples are discarded, pristine trends suggest that the top of the section records a negative carbon isotope excursion that is interpreted as CMBa-c events that straddle the Campanian–Maastrichtian boundary. This interpretation is supported by the lowermost occurrence of planktic foraminifers Rugoglobigerina scotti and Contusotruncana contusa some 30 m above the base of the negative excursion and 10 m below a positive excursion identified as the Maastrichtian M1+ event. Discrepancies in the stratigraphic range of several planktic foraminifer bioevents are highlighted and advocate for the need of many more integrated records of planktic foraminifer and nannofossil biostratigraphy alongside carbon isotope stratigraphy in the eastern Tethys in order to improve regional and global schemes. |
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| Keywords: | Late Cretaceous Plankton diachronism Eastern Tethys |
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