气候变化领域集成服务门户(CCPortal): Magnesium and Lithium Isotopic Evidence for a Remnant Oceanic Slab Beneath Central Tibet

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DOI	10.1029/2019JB018197
	Magnesium and Lithium Isotopic Evidence for a Remnant Oceanic Slab Beneath Central Tibet
	Tian H.-C.; Teng F.-Z.; Hou Z.-Q.; Tian S.-H.; Yang W.; Chen X.-Y.; Song Y.-C.
发表日期	2020
ISSN	21699313
卷号	125 期号:1
英文摘要	The voluminous Eocene postcollisional potassium-rich magmatism in central Tibet is crucial in understanding the deep geodynamic process and related uplift history of the Tibetan Plateau. Here, we present an integrated study of whole-rock Sr-Nd-Mg-Li isotopes and zircon U-Pb ages on two suites of lavas from Duocaima and Nariniya in the northern Qiangtang block. The Duocaima high-K calc-alkaline trachyandesites were formed at ~35 Ma and are enriched in light rare earth elements and large ion lithophile elements. They have slightly lower δ26Mg (−0.41‰ to −0.33‰) and δ7Li (+1.0‰ to +2.6‰) relative to the mantle. Together with their high 87Sr/86Sr(i) (0.7066–0.7067) and low ɛNd(t) (−1.96 to −1.61) values, they most likely originated from the lithospheric mantle previously metasomatized by melts from subducted carbonate-bearing sediments. Model calculation suggests that ~7–11% sediments were added into the mantle via melting. By contrast, the contemporaneous Nariniya adakitic trachytes have higher δ26Mg (−0.13‰ to −0.02‰) and δ7Li (+3.3‰ to +5.4‰) values, as well as higher Pb/Ce and Ba/La ratios, which most likely resulted from the thickened lower crust that was metasomatized by fluids released from downgoing Songpan-Ganzi oceanic slab. Our combined isotopic study suggests the existence of a remnant oceanic slab beneath central Tibetan Plateau during the late Eocene and implies that the initial uplift of central Tibet was before ~38 Ma. ©2019. American Geophysical Union. All Rights Reserved.
英文关键词	Eocene volcanic rocks; fluid and melt metasomatism; Qiangtang; remnant oceanic slab; Sr-Nd-Mg-Li isotopes; uplift
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/188030
作者单位	Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China; Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing, China; Isotope Laboratory, Department of Earth and Space Sciences, University of Washington, Seattle, WA, United States; Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China; State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang, China; MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, China
推荐引用方式 GB/T 7714	Tian H.-C.,Teng F.-Z.,Hou Z.-Q.,et al. Magnesium and Lithium Isotopic Evidence for a Remnant Oceanic Slab Beneath Central Tibet[J],2020,125(1).
APA	Tian H.-C..,Teng F.-Z..,Hou Z.-Q..,Tian S.-H..,Yang W..,...&Song Y.-C..(2020).Magnesium and Lithium Isotopic Evidence for a Remnant Oceanic Slab Beneath Central Tibet.Journal of Geophysical Research: Solid Earth,125(1).
MLA	Tian H.-C.,et al."Magnesium and Lithium Isotopic Evidence for a Remnant Oceanic Slab Beneath Central Tibet".Journal of Geophysical Research: Solid Earth 125.1(2020).