Petrogenesis and tectonic significance of the early Paleozoic Delenuoer ophiolite in the Central Qilian Shan,northeastern Tibetan Plateau |
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| Institution: | 1. Key Laboratory of Mineral Resources in Western China, School of Earth Sciences, Lanzhou University, Lanzhou, 730000, China;2. State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing, 100083, China;3. Changqing Branch, Research Institute of Bureau of Geophysical Prospecting, China National Petroleum Corporation, Xi’an, 710021, China;4. Geological Survey of Gansu Province, Lanzhou, 730000, China;5. No.2 Geology and Mineral Exploration Team, Gansu Provincial Bureau of Geology and Mineral Exploration and Development, Lanzhou, 730000, China |
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| Abstract: | The newly discovered early Paleozoic Delenuoer ophiolite, in the western margin of the Central Qilian Shan, is composed of serpentinized peridotite, cumulate gabbro, diabase, massive basalt, and pillow basalt. This study presents geochronological and geochemical data for the cumulate gabbro and basalt. LA–ICP–MS U–Pb dating of zircons from the cumulate gabbro yielded a magmatic crystallization age of 472 ?± ?4 ?Ma. The basalts have normal mid-ocean ridge basalt (N-MORB) compositions and a narrow range of εNd(t) values (+4.5 to ?+5.3), which indicates they were derived from a depleted mantle source. On the basis of regional geological constraints, it is proposed that the Delenuoer ophiolite is a westward extension of the South Ophiolite Belt (Yushigou–Youhulugou–Donggou–Dongcaohe Ophiolite Belt) in the North Qilian Shan. The Delenuoer ophiolite, along with the Gulangxia–Delenuoer fault, defines the westernmost part of the tectonic boundary between the North and Central Qilian Shan. This ophiolite may have formed during southward subduction of the Qilian Ocean slab during the early Paleozoic. |
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| Keywords: | Ophiolite Delenuoer Central Qilian Shan Early Paleozoic Tectonic boundary |
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