Thermo-mechanical modeling of the obduction process based on the Oman Ophiolite case |
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| Institution: | 1. Institut des sciences de la Terre, University of Lausanne, 1015 Lausanne, Switzerland;2. ISTEP, UMR CNRS 7193, UPMC Sorbonne Universités, 75252 Cedex 05 Paris, France;3. Geosciences Rennes, UMR CNRS 6118, Université de Rennes 1, 35042 Rennes Cedex, France;4. Applied Geosciences, GUtech, PO Box 1816, Athaibah, PC 130, Sultanate of Oman;5. Institute of Geophysics, ETH Zürich, Sonneggstrasse 5, 8092 Zürich, Switzerland;1. University of Bergen, Department of Earth Science, P.O. Box 7803, N-5020 Bergen, Norway;2. Norwegian Polar Institute, Fram Centre, N-9296 Tromsø, Norway;3. British Geological Survey, Nicker Hill, Keyworth, Nottingham NG12 5GG, UK;4. Geoscience Centre, University of Göttingen, Goldschmidtstr. 3, 37077 Göttingen, Germany;1. Sorbonne Universités, UPMC Univ Paris 06, UMR 7193, Institut des Sciences de la Terre Paris (iSTeP), F-75005 Paris, France;2. CNRS, UMR 7193, Institut des Sciences de la Terre Paris (iSTeP), F-75005 Paris, France;3. Dublin Institute for Advanced Studies, Geophysics Section, 5 Merrion Square, Dublin 2, Ireland;4. Géosciences Rennes, CNRS UMR 6118, Université de Rennes 1, F-35042 Rennes, France;1. Institute for Geothermal Sciences, Graduate School of Science, Kyoto University, Beppu 874-0903, Japan;2. Department of Natural History Sciences, Hokkaido University, Sapporo 060-0808, Japan;3. Department of Earth Sciences, Kanazawa University, Kanazawa 920-1192, Japan;4. Research and Development Center for Ocean Drilling Science, JAMSTEC, Yokosuka 237-0061, Japan;5. Department of Geology, Niigata University, Niigata 950-2182, Japan;6. Department of Civil and Earth Resources Engineering, Kyoto University, Kyoto 606-8501, Japan;7. Graduate School Division of Science and Engineering, University of Toyama, Toyama 930-8555, Japan;8. Graduate School of Engineering, Hokkaido University, Sapporo 060-0808, Japan;1. School of Earth Science and Geological Engineering, Sun Yat-Sen University, Guangzhou 510275, China;2. Key Laboratory of Computational Geodynamics, College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China;3. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China;4. Department of Earth Sciences, University of St Andrews, North Street, St Andrews KY16 9AL, UK;5. Centre for Exploration Targeting, School of Earth and Environment, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia;6. Institute of Geophysics, Department of Earth Sciences, ETH-Zurich, 8092 Zurich, Switzerland |
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| Abstract: | Obduction emplaces regional-scale fragments of oceanic lithosphere (ophiolites) over continental lithosphere margins of much lower density. For this reason, the mechanisms responsible for obduction remain enigmatic in the framework of plate tectonics. We present two-dimensional (2D) thermo-mechanical models of obduction and investigate the possible dynamics and physical controls of this process. Model geometry and boundary conditions are based on available geological and geochronological data and numerical modeling results are validated against petrological and structural observations of the Oman (Semail) Ophiolite. Our model reproduces the stages of oceanic subduction initiation away from the Arabian margin, the emplacement of the Oman Ophiolite on top of it, and the domal exhumation of the metamorphosed margin through the ophiolitic nappe. A systematic study indicates that 350–400 km of bulk shortening provides the best fit for both maximum pressure–temperature conditions of the metamorphosed margin (1.5–2.5 GPa/450–600 °C) and the dimension of the ophiolitic nappe (~ 170 km width). Our results confirm that a thermal anomaly located close to the Arabian margin (~ 100 km) is needed to initiate obduction. We further suggest that a strong continental basement rheology is a prerequisite for ophiolite emplacement. |
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