Petro-tectonic evolution of metamorphic sole of the Semail ophiolite,UAE |
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| Institution: | 1. Geology Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Republic of Korea;2. Department of Earth System Sciences, Yonsei University, Seoul 03722, Republic of Korea;3. School of Earth Sciences and Resources, China University of Geosciences, Beijing, 29 Xueyuan Road, Beijing 100083, China;4. Centre for Tectonics, Resources and Exploration, Department of Earth Sciences, University of Adelaide, SA 5005, Australia;5. Department of Geology, Kyungpook National University, Daegu 41566, South Korea;1. Tethys Research Center, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. Center for Excellence in Tibetan Plateau Earth Sciences, China;3. Xinjiang Research Center for Mineral Resources, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China;4. Laboratory of Structural and Sedimentological Reservoir Geology, Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China;5. University of Chinese Academy of Sciences, Beijing 100049, China;6. Department of Geology, University of Leicester, Leicester LE1 7RH, UK;7. Institute of Geology and Mineralogy SB RAS, Novosibirsk 630090, Russia;8. Novosibirsk State University, Pirogova 1, Novosibirsk 630090, Russia;1. Xinjiang Research Center for Mineral Resources, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. Xinjiang Key Laboratory of Mineral Resources and Digital Geology, Urumqi, Xinjiang 830011, China;4. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;5. Institute of Geology, Kyrgyz National Academy of Science, 30 Erkindik Avenue, Bishkek 720040, Kyrgyzstan;6. Research Center for Ecology and Environment of Central Asia, Chinese Academy of Sciences, Bishkek 720040, Kyrgyzstan;1. Earth Research Institute, University of California, Santa Barbara, CA 93106, USA;2. Department of Earth Science, University of California, Santa Barbara, CA 93106, USA;3. Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA;4. Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, UK;5. Department of Earth and Environmental Studies, Columbia University, Lamont Doherty Earth Observatory, Palisades, NY 10964, USA;1. Geology Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Republic of Korea;2. Department of Earth and Environmental Sciences and The Earth and Environmental Science System Research Center, Chonbuk National University, Jeonju 561-756, Republic of Korea |
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| Abstract: | The Semail ophiolite located in the eastern part of the Arabian platform preserves remnants of ocean plate stratigraphy and related metamorphic sole. To understand the petro-tectonic evolution of a metamorphic sole during subduction to obduction processes, here we investigate the garnet metagabbros from the metamorphic sole and the tonalites which intruded the mantle section of the Khor Fakkan Block. We present results from petrology, geochemistry, zircon U-Pb, Hf and O isotope analyses and phase equilibria modeling. The garnet metagabbro samples have E-MORB-type enriched-mantle compositions with zircon dates of ca. 89–96 Ma, and positive εHf(t) values ranging from 5.6 to 10.0. The tonalite is peraluminous with those range of ca. 87–92 Ma, and a range of positive εHf(t) values of 5.1–10.0. The similarity in εHf values from both the garnet metagabbro and tonalite samples suggests a strong relevance to their mantle source, indicating the role of subducted material during their formation. In contrast, the δ18O(zircon) values show distinctly different values of high δ18O(zircon) of ~13–16‰ for the tonalite and ~ 5–8‰ for the metagabbro samples, reflecting variations in the role of surface-derived source materials. The phase equilibria modeling of the garnet metagabbro shows high-pressure amphibolite facies metamorphism that preceded the peak granulite facies metamorphism, followed by lower pressure hydration and decompression. This clockwise P-T path might reflect partial melting and differentiation of mantle wedge section above subducted slab. Our results provide insights into the complex processes within a supra-subduction zone, implying differences in degree of partial melting of the ocean plate stratigraphic sequences including recycled oceanic slab and surface-derived marine sediments that were subsequently interacted with hydrothermally altered mantle at a mantle wedge during subduction to obduction processes that formed the Semail ophiolite during the Upper Cretaceous. |
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