气候变化领域集成服务门户(CCPortal): Subduction initiation of the SE Paleo-Asian Ocean: Evidence from a well preserved intra-oceanic forearc ophiolite fragment in central Inner Mongolia, North China

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DOI	10.1016/j.epsl.2020.116087
	Subduction initiation of the SE Paleo-Asian Ocean: Evidence from a well preserved intra-oceanic forearc ophiolite fragment in central Inner Mongolia, North China
	Li Y.; Wang G.; Santosh M.; Wang J.; Dong P.; Li H.
发表日期	2020
ISSN	0012821X
卷号	535
英文摘要	Subduction of oceanic lithosphere is the primary driver of plate tectonics on Earth. However, one of the least understood aspects of plate tectonics is how subduction zones initiate, due to the lack of recognition of subduction initiation records in many ophiolites. Here we report a newly recognized complete magmatic record including Early Carboniferous fore-arc basalts (FABs), transitional lavas and boninites in the Diyanmiao ophiolite zone in central Inner Mongolia, North China. The stratigraphy and chemo-temporal relations of the suite are identical to those of the Izu–Bonin–Mariana (IBM) forearc as well as the ophiolite suites associated with subduction initiation such as Semail in Oman. In the Diyanmiao suite, the FABs are exposed over a large area, overlying gabbroic rocks of the ophiolite, and underlain by transitional lavas and boninites from bottom to top. Zircon U–Pb geochronology of the FABs shows a mean age of 335.6±2.6 Ma. The Diyanmiao FABs are mainly aphyric, with variolitic groundmass texture, and pillow structure. The boninites (∼328 Ma) are strongly porphyritic with skeletal olivine crystal, clinopyroxene and orthopyroxene phenocrysts. The major and trace element and Sr–Nd isotopic characteristics of FABs, transitional lavas and boninites in the Diyanmiao ophiolite are comparable to those of corresponding rocks in the IBM forearc. The FABs display compositions similar to those of the most depleted mid-ocean ridge basalts (MORB), but with lower Ti/V ratios, suggesting slightly higher concentrations of fluid-soluble elements than MORB. The Diyanmiao transitional lavas have transitional compositions between FABs and boninites, and have higher large ion lithophile elements (LILEs) and lower high field strength elements (HFSEs) than FABs. The boninites are characterized by significant depletion of Ti, heavy rare earth element (HREE), and HFSE and are more LILE-enriched. This volcanic sequence is akin to that in the Mariana forearc, suggesting that the Diyanmiao FABs might record initial volcanism associated with subduction initiation in the southeastern Paleo-Asian Ocean during Early Carboniferous (∼335.6 Ma). We infer that the primary magmas of the Diyanmiao FABs were generated by partial melting of upwelling mantle associated with decompression during forearc spreading with little or no slab input. Progressive subduction of the Paleo-Asian oceanic slab (ca. 328 Ma), and flushing by slab-derived hydrous fluids resulted in melting of the more depleted, residual mantle at (probably) shallower levels generating the boninites. © 2020 Elsevier B.V.
关键词	Early Carboniferous forearc basalt Inner Mongolia ophiolite Paleo-Asian Ocean subduction initiation
英文关键词	Basalt; Geochronology; Melting; Oceanography; Plates (structural components); Rare earths; Silicate minerals; Stratigraphy; Structural geology; Tectonics; Textures; Zircon; Early Carboniferous; Forearc; Inner Mongolia; ophiolite; Paleo-Asian Ocean; Subduction initiation; Trace elements; basalt; Carboniferous; forearc basin; mantle upwelling; ophiolite; partial melting; plate tectonics; subduction zone; uranium-lead dating; volcanism; zircon; China; Nei Monggol
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202730
作者单位	School of Nature Resources, Hebei GEO University, Shijiazhuang, 050031, China; School of the Earth Sciences and Resources, China University of Geosciences, Beijing, 100083, China; Department of Earth Sciences, University of Adelaide, Adelaide, SA 5005, Australia
推荐引用方式 GB/T 7714	Li Y.,Wang G.,Santosh M.,et al. Subduction initiation of the SE Paleo-Asian Ocean: Evidence from a well preserved intra-oceanic forearc ophiolite fragment in central Inner Mongolia, North China[J],2020,535.
APA	Li Y.,Wang G.,Santosh M.,Wang J.,Dong P.,&Li H..(2020).Subduction initiation of the SE Paleo-Asian Ocean: Evidence from a well preserved intra-oceanic forearc ophiolite fragment in central Inner Mongolia, North China.Earth and Planetary Science Letters,535.
MLA	Li Y.,et al."Subduction initiation of the SE Paleo-Asian Ocean: Evidence from a well preserved intra-oceanic forearc ophiolite fragment in central Inner Mongolia, North China".Earth and Planetary Science Letters 535(2020).