Chinese Science Bulletin

, 46:1732 | Cite as

Polybaric partial melting in the continental mantle: Evidence from mantle xenoliths from Qilin Guangdong Province

  • Xu Yigang
  • Yan Wen
  • Sun Min
  • Liu Ying
  • He Zaicheng
  • Shi Lanbin


The extremely low Ti content (160–245 μg/g) in clinopyroxene in some spinel peridotites from Qilin, South China is indicative of high degree of partial melting, inconsistent with their relatively high clinopyroxene modes (7.4%–12.4%). These clinopyroxenes show fractionated HREE patterns ((Gd/Yb)n<0.2), suggesting the involvement of garnet in the melting regime. These REE patterns can be modeled as residues of 22%–23% fractional melting from a primitive mantle, first in garnet stability field (12%) then continuing in spinel stability field (10%–11%) after breakdown of garnet to pyroxenes and spinel. Such a polybaric melting suggests the lithospheric thinning and rapid mantle upwelling in south China during the Cenozoic. This is consistent with the dominant MORB-OIB isotopic signature and high thermal gradient of the lithospheric mantle in this region, and supports the contention that the formation of South China Sea basin is related to southward migration of continental lithosphere extension, rather than passive back-arc basin.


mantle xenoliths trace element polybaric melting Qilin 


  1. 1.
    Klein, E. M., Langmuir, C. H., Global correlation of ocean ridge basalt chemistry with axial depth and crustal thickness, J. Geophy. Res., 1987, 92: 8089.CrossRefGoogle Scholar
  2. 2.
    McKenzie, D. P., Bickle, M. J., The volume and composition of melt generated by extension of the lithosphere, J. Petrol., 1988, 29: 625.Google Scholar
  3. 3.
    White, R. S., McKenzie, D. P., Mantle plume and continental flood basalts, J. Geophys. Res., 1995, 100: 17543.CrossRefGoogle Scholar
  4. 4.
    Hauri, E. H., Hart, S. R., Constraints on the melt migration from mantle plumes: a trace element study of peridotite xenoliths from Savai’i, Western Samoa, J. Geophys. Res., 1994, 99: 24301.Google Scholar
  5. 5.
    Witt-Eickschen, G. E., Kramm, U., Mantle upwelling and metasomatism beneath Central Europe: Geochemical and isotopic constraints from Mantle xenoliths from the Rhon (Germany), J. Petrol., 1997, 38: 479.CrossRefGoogle Scholar
  6. 6.
    Xu, X., O’Reilly, S. Y., Zhou, X. et al., A xenolith-derived geotherm and the crust-mantle boundary at Qilin, southeastern China, Lithos., 1996, 38: 41.CrossRefGoogle Scholar
  7. 7.
    Xu, Y. G., The trace element signature of the mantle-derived xenoliths from Qilin, Guangdong province and its geological significance, Guangdong Geology (in Chinese), 1998, 13: 39.Google Scholar
  8. 8.
    Xu, X., O’Reilly, S. Y., Griffin, W. L. et al., Genesis of young lithospheric mantle in southeastern China: an LAM-ICPMS trace element study, J. Petrol., 2000, 41: 111.CrossRefGoogle Scholar
  9. 9.
    Xu, Y. G., Distribution of trace elements in spinel and garnet peridotites, Science in China, Series D, 2000, 43: 166.CrossRefGoogle Scholar
  10. 10.
    Johnson, K. T. M., Dick, H. J. B., Shimizu, N., Melting in the oceanic upper mantle: An ion microprobe study of diopsides in abyssal peridotites, J. Geophy. Res., 1990, 95: 2661.CrossRefGoogle Scholar
  11. 11.
    Sun, S. S., McDonough, W. F., Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes, Magmatism in the Ocean Basins (eds. Saunders, A. D., Norry, M. J.), London: Geological Society Special Publication, 1989. 313–345.Google Scholar
  12. 12.
    Navon, O., Stolper, E. Geochemical consequence of melt percolation: the upper mantle as a chromatographic column, J. Geol., 1987, 95: 285.CrossRefGoogle Scholar
  13. 13.
    Xu, Y. G., Menzies, M. A., Vroon, P. et al., Texture-temperature-Geochemistry relationship in the upper mantle as revealed from spinel peridotite xenoliths from Wangqing, NE China, J. Petrol., 1998, 39: 469.CrossRefGoogle Scholar
  14. 14.
    Johnson, K. T. M., Experimental determination of partition coefficients for rare earth and high-field-strength elements between clinopyroxene, garnet and basaltic melt at high pressures, Contrib. Mineral. Petrol., 1998, 133: 60.CrossRefGoogle Scholar
  15. 15.
    Kinzler, R. J., Melting of mantle peridotite at pressure approaching the spinel to garnet transition: application to mid-ocean ridge petrogenesis, J. Geophys. Res., 1997, 102: 853.CrossRefGoogle Scholar
  16. 16.
    Walter, M. J., Melting of garnet peridotite and the origin of komatiitic and depleted lithosphere, J. Petrol., 1998, 39: 29.CrossRefGoogle Scholar
  17. 17.
    Xu, Y. G., Lin, C. Y., Shi, L. B., The geotherm of the lithosphere beneath Qilin, SE China: A re-appraisal and implications for P-T estimation of Fe-rich pyroxenites, Lithos., 1999, 47: 181.CrossRefGoogle Scholar
  18. 18.
    Zou, H. P., Li, P. L., Rao, C. T., Geochemistry of Cenozoic volcanic rocks in ZhuJiangkou Basin and its geodynamic significance. Geochimica (in Chinese), 1995, 18(suppl): 33.Google Scholar
  19. 19.
    Chung, S. L., Cheng, H., Jahn, B. M. et al., Major and trace element, Sr-Nd isotope constraints on the origin of Paleogene volcanism in South China prior to the South China Sea opening, Lithos., 1997, 40: 203.CrossRefGoogle Scholar
  20. 20.
    Fan, W. M., Menzies, M. A., Yin, H. H. et al., The nature and process of the deep lithosphere beneath southeast China, Geotectinica et Metallogenia (in Chinese), 1993, 17: 23.Google Scholar

Copyright information

© Science in China Press 2001

Authors and Affiliations

  • Xu Yigang
    • 1
  • Yan Wen
    • 2
  • Sun Min
    • 3
  • Liu Ying
    • 1
  • He Zaicheng
    • 1
  • Shi Lanbin
    • 4
  1. 1.Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhouChina
  2. 2.Institute of South China OceanographyChinese Academy of SciencesGuangzhouChina
  3. 3.Department of Earth SciencesThe University of Hong KongChina
  4. 4.Institute of GeologyState Seismological BureauBeijingChina

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