Where are the remnants of a Jurassic ocean in the eastern Mediterranean region? |
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| Institution: | 1. Department of Geological Engineering, Karadeniz Technical University, 61080 Trabzon, Turkey;2. Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA;3. Department of Earth Sciences, University of Adelaide SA 5005, Australia;4. School of Earth Sciences and Resources, China University of Geosciences, 29 Xueyuan Road, Beijing 100083, China;5. CAS Key Laboratory of Crust–Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China;6. Korea Basic Science Institute, YangCheong 804-1, Ochang, Cheongwon, Chungbuk 363-883, South Korea;7. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;1. Munzur University, Department of Geological Engineering, 62000 Tunceli, Turkey;2. Middle East Technical University, Department of Geological Engineering, 06800 Ankara, Turkey;3. University of Notre Dame, Department of Civil and Environmental Engineering and Earth Sciences, South Bend, Indiana 46556, USA;1. Dipartimento di Scienze, Università Roma Tre, Roma, Italy;2. Géosciences Rennes, UMR 6118, Université de Rennes 1, Rennes, France;3. Institut für Geowissenschaften, Goethe-Universität, Frankfurt am Main, Germany;4. Institut für Mineralogie und Kristallchemie, Universität Stuttgart, Stuttgart, Germany;1. Istanbul Technical University, Department of Geological Engineering, ?stanbul 34469, Turkey;2. University of Georgia, Department of Geology, Athens, GA 30602, USA;3. Auburn University, Department of Geology, AL 36849, USA |
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| Abstract: | The subduction polarity of Tethyan oceanic lithosphere during Jurassic is a controversial topic in relation to the geodynamic evolution of the Alpine–Himalayan system. We present new geological, geochemical and zircon U–Pb data from four different regions of the Eastern Pontides Orogenic Belt, a key area of the Alpine–Himalayan system. We discuss the origin of the magmatism and also the existence of an ocean in the eastern Mediterranean region during the Jurassic period. Jurassic intrusions, predominantly gabbro, tonalite and minor diorite, are well exposed in the southern and axial zones of the orogenic belt. Thermobarometry indicates that high-pressure (6–10 kb) crystallization of these intrusions occurred at temperatures of 1183–1250 °C. Zircon U–Pb dating from 10 samples show ages between 195 and 165 Ma, indicating that magmatism occurred between Sinemurian and Callovian time. We characterize the intrusions from electron microprobe, zircon geochronology, and whole rock and Sr, Nd, and Pb isotopes. Our data show that the studied intrusions are broadly tholeiitic, except for two calc-alkaline bodies, and formed in an arc-related setting with minimal involvement of older crust or sediment.The most widely accepted model proposes that the ultramafic–mafic rocks exposed between the Pontide arc and the Tauride belt are remnants of a Jurassic Penrose-type and/or suprasubduction zone ophiolite. However, new zircon U–Pb age data from mafic lithologies cutting the Kop ultramafic massif do not support this model and clearly indicate that the ultramafic lithologies are Paleozoic or older in age and are not remnants of a Jurassic ocean that known as ‘’Northern Branch of Neotehtys”. |
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