DOI: 10.1016/j.epsl.2021.116760
论文题名: First evidence of eclogites overprinted by ultrahigh temperature metamorphism in Everest East, Himalaya: Implications for collisional tectonics on early Earth
作者: Wang J.-M. ; Lanari P. ; Wu F.-Y. ; Zhang J.-J. ; Khanal G.P. ; Yang L.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 558 语种: 英语
中文关键词: 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
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165703
Appears in Collections: 气候变化与战略
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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
Recommended Citation:
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]. Earth and Planetary Science Letters,2021-01-01,558