Advances in Earth Science ›› 2004, Vol. 19 ›› Issue (5): 722-731. doi: 10.11867/j.issn.1001-8166.2004.05.0722

Special Issue: 青藏高原研究——青藏科考虚拟专刊

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EQUILIBRIUM P-T CONDITIONS OF MAFIC DEEP-DERIVED ENCLAVES AND ITS SIGNIFICANCE IN LIUHE-XIANGDUO AREA OF EASTERN TIBET

WEI Qi-rong 1,2, WANG Jiang-hai 2   

  1. 1.College of Materials Science & Chemical Engineering, China University of Geosciences,Wuhan 430074, China; 2. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou510640, China
  • Received:2003-06-05 Revised:2003-10-17 Online:2004-12-20 Published:2004-10-01

WEI Qi-rong, WANG Jiang-hai. EQUILIBRIUM P-T CONDITIONS OF MAFIC DEEP-DERIVED ENCLAVES AND ITS SIGNIFICANCE IN LIUHE-XIANGDUO AREA OF EASTERN TIBET[J]. Advances in Earth Science, 2004, 19(5): 722-731.

Based on electron microprobe analyses of garnets, pyroxenes, amphiboles and plagioclases from mafic deep-derived enclaves in Liuhe-Xiangduo area, eastern Tibet, calculated equilibrium temperatures of the enclaves by Grt-Cpx geothermometers (TEG79, TP85,TK88, and TR2000), Grt-Hblgeothermometers (TGP84and TRV2000), and Hbl-Plgeothermometers (TBH90), and equilibrium pressures by aluminum-in-amphibole geobarometrys (PAl-in-Hbl). The results showed that equilibrium temperatureand pressureconditions of garnet diopsidite, garnet amphibolite, garnet hornblendite, amphiboliteand hornblenditewere 770~920 ℃ and 0.83~1.50 GPa (equivalent to27~50 km depth), 730~950 ℃ and 0.85~1.04 GPa (28~34 km), 720~900 ℃ and 0.74~1.32 GPa (24~44 km), 512~753 ℃ and 0.71~0.98 GPa (23~32 km), and 0.60~0.84 GPa (20~28 km). The P-T conditions in the enclaves revealed the former three types of enclaves came from low-crust with higher P-T (720~950 ℃ and 0.74~1.50 GPa), and the latter two derived from middle-crust with lower P-T ( 510~735 ℃ and 0.60~0.98 GPa). The P-Tconditionof enclaves still indicated the source depth of the high-K magma is 50km at least. 

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