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Chinese Science Bulletin

, Volume 47, Issue 11, pp 881–886 | Cite as

Discovery of ultrahighpressure magnesite-bearing garnet lherzolite (>3.8 GPa) in the Altyn Tagh, Northwest China

  • Liu Liang 
  • Sun Yong 
  • Xiao Peixi 
  • Che Zicheng 
  • Luo Jinhai 
  • Chen Danling 
  • Wang Yan 
  • Zhang Anda 
  • Chen Liang 
  • Wang Yonghe 
Paper

Abstract

Magnesite-bearing garnet lherzolite from the Altyn Tagh, associated with garnet pyroxenite, and garnet-bearing felsic gneiss, crops out as lenses in Proterozoic gneiss about 100 km east of the Jianggelasayi River. The garnet lherzolite, together with the eclogite in western Jianggelasayi, composes a high-pressure to ultrahighpressure metamorphic belt in the southern margin of the Altyn Tagh. Parageneses of minerals from magnesite-bearing garnet lherzolite indicate that the rock evolved a multi-stage metamorphism. The peak-stage metamorphism produces an assemblage of Grt+Ol+Opx+Cpx±Mgs, in which Al2O3 content of Opx is very low (0.30–0.66wt%). The calculated P-T condition of the peak stage is 3.8–5.1GPa and 880–970°C, some exsolution rods of clinopy roxene and rutile occur in the Grt and magnesite is rimed by dolomite and orthopyroxene, all implying that the peak stage was a UHP metamorphic process. Together with regional geological studies, isotopic dating and the discovery of coesite inclusions in zircon separates from felsic gneiss from the northern margin of the Qaidam Basin, the presence of a very long UHP metamorphic belt in northwest China is suggested.

Keywords

garnet lherzolite magnesite UHP metamorphism Altyn Tagh Mountains 

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Copyright information

© Science in China Press 2002

Authors and Affiliations

  • Liu Liang 
    • 1
  • Sun Yong 
    • 1
  • Xiao Peixi 
    • 2
  • Che Zicheng 
    • 1
  • Luo Jinhai 
    • 1
  • Chen Danling 
    • 1
  • Wang Yan 
    • 1
  • Zhang Anda 
    • 1
  • Chen Liang 
    • 1
  • Wang Yonghe 
    • 2
  1. 1.Key Laboratory of Continental Dynamics of the Ministry of EducationNorthwest UniversityXi’anChina
  2. 2.The Northwest Institute of Geology and Mineral ResourcesXi’anChina

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