Geochemical and geochronological constraints on the origin of the Sabzevar ophiolites (NE Iran): forced far-field subduction initiation in the upper-plate of the Neo-Tethys subduction zone |
| |
| Institution: | 1. Department of Geology, Faculty of Science, Imam Khomeini International University, Qazvin, Iran;2. Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China;3. Dipartimento di Scienze della terra, Sapienza Università di Roma, Roma, Italy;4. Istituto di Geologia Ambientale e Geoingegneria (IGAG) – CNR, c/o Dipartimento di Scienze della Terra, Sapienza Università Roma, Roma, Italy;5. Dipartimento di Scienze, Università Roma Tre, Roma, Italy;1. General Directorate of Industrial Zones, Ministry of Industry and Technology, Ankara, Turkey;2. Department of Geological Engineering, ?stanbul University-Cerrahpa?a, ?stanbul, Turkey;3. Department of Geological Engineering, Faculty of Mines, ?stanbul Technical University, ?stanbul, Turkey;1. College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China;2. Institute of Subsurface Energy Systems, Clausthal University of Technology, Clausthal Zellerfeld 38678, Germany;3. State Key Laboratory of Geohazard Prevention and Geoenvironmental Protection, Chengdu University of Technology, Chengdu 610059, China;4. Department of Petroleum & Gas Engineering, University of Engineering & Technology, 54890 Lahore, Pakistan;5. Sichuan bureau of geology & mineral resources - 402 Team, Chengdu 611743, China;1. EXPEC Advanced Research Center, Saudi Aramco, Dhahran, Saudi Arabia;2. SA Reservoir Management Department, Saudi Aramco, Dhahran, Saudi Arabia;1. Laboratório de Estudos Tectônicos (LESTE), Universidade Federal dos Vales do Jequitinhonha e Mucuri, Campus JK, MGT 367, Km 583, n° 5000 Alto da Jacuba, Diamantina, MG 39100-000, Brazil;2. Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, Bauxita, Ouro Preto, MG, 35.400-000. Brazil |
| |
| Abstract: | The Sabzevar ophiolites, located at the northern margin of the Central-East Iranian microcontinent (CEIM), are part of the Mesozoic-Paleogene Neotethyan suture zone developed along the Alpine-Himalayan convergence zone. These ophiolites consist mostly of oceanic lithospheric remnants, covered by early Campanian-late Maastrichtian volcano-sedimentary successions. A distinctive characteristic of the Sabzevar ophiolites is the occurrence of mafic dike swarms (gabbros, gabbronorites and diorites) with forearc-arc-tholeiitic geochemical signature, intruding the mantle section. Occurrence of orthopyroxene, development of pegmatitic texture, crystallization of clinopyroxene prior to plagioclase, and the presence of anorthite-rich plagioclase imply relatively high H2O content in the magmatic plumbing system. Rare plagiogranites (tonalite and trondhjemite compositions) show geochemical features compatible with a supra-subduction setting, whereas late (hornblende-bearing) gabbro dikes show a within-plate signature. The bimodal geochemical affinity (subduction vs. intraplate) is also attested by clinopyroxene compositions. The gabbroic, plagiogranitic and gabbronoritic samples yield Early Cretaceous SHRIMP zircon U-Pb ages of 96.7 ± 1, 98 ± 1 and 94 ± 1 Ma, respectively. A progression from tholeiitic MORB-like to more depleted high-Mg andesite and eventually alkaline affinities is here proposed, framing the magma evolution as generated in an evolving forearc setting that post-dated (of at least 9 Myr) the formation of the metamorphic sole during the infant stages of subduction of the Sabzevar Ocean.A scenario of far-field forced subduction initiation of the Sabzevar Ocean is proposed as consequence of propagation of the residual stresses transmitted from the Arabia-Eurasia convergence zone across the CEIM during Cretaceous times (Albian-Campanian). |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
