气候变化领域集成服务门户(CCPortal): First evidence of eclogites overprinted by ultrahigh temperature metamorphism in Everest East, Himalaya: Implications for collisional tectonics on early Earth

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DOI	10.1016/j.epsl.2021.116760
	First evidence of eclogites overprinted by ultrahigh temperature metamorphism in Everest East, Himalaya: Implications for collisional tectonics on early Earth
	Wang J.-M.; Lanari P.; Wu F.-Y.; Zhang J.-J.; Khanal G.P.; Yang L.
发表日期	2021
ISSN	0012821X
卷号	558
英文摘要	Modern-style plate tectonics, often characterised by subduction, is a fundamental dynamic process for planet Earth. Subduction related eclogites are widely used to indicate initiation of plate tectonics or whether different tectonic regimes dominated Earth history. However, such markers are commonly overprinted in ancient metamorphic terranes and rarely preserved even in most Phanerozoic mountain belts. This study tries to reveal the detailed burial and exhumation processes that formed granulitized eclogites in the Everest east region, central Himalaya, so as to explore the tectonic regimes recorded by similar rocks on early Earth. Robust Pressure-Temperature-time paths were achieved by studying the mineral relicts (Omp, Jd ∼29%), high-temperature mineral textures (Sil-Crd-Qz-Spl-Mesoperthite assemblage, rutile exsolution in biotite), and multiple thermobarometry and petrochronology of eclogites and metapelites. Results show that these eclogites underwent eclogitization at conditions of 730–770 °C and ∼20 kbar (∼11 °C/km) at ∼30 Ma and were overprinted by a heating and decompression path to ultrahigh temperature (UHT) conditions of 6–11 kbar and 900–970 °C (∼40 °C/km) during 25–15 Ma. The resulting exhumation rate (2–3 mm/yr) is slow and prolonged (10–15 Myr) (U)HT favoured re-equilibration of the eclogitic mineral assemblage and textures. The obtained UHT conditions, the first time ever reported for the Himalaya, were induced by combined effects of over-thickened (∼60 km) radioactive felsic crust and thinning of lithosphere to <90 km. This case study provides a critical example to understand the heat sources and timescale of UHT condition during continental collision. By comparing with the western Himalaya eclogites, we suggest that formation of cold vs. granulitized continental eclogites during the Himalayan orogeny is caused by different crustal thickness (normal ∼30 km vs. over-thickened ∼60 km) due to different collisional stages (infant vs. mature). In a wider perspective, ancient eclogites were commonly granulitized by stacking into the over-thickened orogenic crust during mature continental collision. According to similar granulitized eclogites preserved on early Earth, Himalaya-type continental subduction/collision should have become a global pattern during the Paleoproterozoic (2.0–1.8 Ga). © 2021 Elsevier B.V.
关键词	continental collision crustal thickening eclogite Himalaya modern-style plate tectonics ultrahigh temperature
英文关键词	Mica; Oxide minerals; Structural geology; Tectonics; Textures; Titanium dioxide; Continental collisions; Continental subductions; Crustal thickness; High temperature minerals; Mineral assemblage; Pressure-temperature-time paths; Re-equilibration; Ultrahigh temperature; Earth (planet); continental collision; crustal thickening; eclogite; orogeny; plate tectonics; tectonic setting; ultrahigh temperature metamorphism; Himalayas
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/203325
作者单位	State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China; Institute of Geological Sciences, University of Bern, Bern, 3012, Switzerland; School of Earth and Space Sciences, Peking University, Beijing, 100871, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100029, China
推荐引用方式 GB/T 7714	Wang J.-M.,Lanari P.,Wu F.-Y.,et al. First evidence of eclogites overprinted by ultrahigh temperature metamorphism in Everest East, Himalaya: Implications for collisional tectonics on early Earth[J],2021,558.
APA	Wang J.-M.,Lanari P.,Wu F.-Y.,Zhang J.-J.,Khanal G.P.,&Yang L..(2021).First evidence of eclogites overprinted by ultrahigh temperature metamorphism in Everest East, Himalaya: Implications for collisional tectonics on early Earth.Earth and Planetary Science Letters,558.
MLA	Wang J.-M.,et al."First evidence of eclogites overprinted by ultrahigh temperature metamorphism in Everest East, Himalaya: Implications for collisional tectonics on early Earth".Earth and Planetary Science Letters 558(2021).