青藏东缘马关地幔岩包体的岩石学与矿物学研究

Translated title of the contribution: Study on petrology and mineralogy of pyrolite xenolith in Maguan area, eastern Tibet

Qi Rong Wei*, De Wei Li, Jian Ping Zheng, Jiang Hai Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Study on petrology and mineral chemical compositions of pyrolite xenoliths from Cenozoic high-K igneous rocks in Maguan area, eastern Tibet showed that the pyrolite xenolith belonged to spinel-phase lherzolite. The rock type was mainly spinel-lherzolite, with mineral assemblages of Ol + Opx + Cpx + Spl, and minor phlogolite and hornblende. Olivine was mainly chrysolite, and a little of forsterite, Fo value ranged from 89.72 to 90.47, and Mg# from 89.75 to 90.51. En numerator in orthopyroxene ranged from 88.00 to 89.59, Mg# value from 90.21 to 91.16 and Cr# from 3.31 to 6.23. Clinopyroxene, mainly belonged to diopside with enstatite diopside, was characterized by high Ca (wCaO from 18.71% to 20.78%), high Al (wAl2O3 6.00% to 7.30%, high Mg# value (89.93 to 91.57), and low Cr# value (5.13 to 8.74). Spinel belonged to chromspinell. w(Cr2O3) in spinel from 7.62% to 12.88%. Mineral chemical composition from pyrolite xenolith in Maguan area indicated that spinel-lherzolite xenoliths belonged to type-A peridotite enclaves and the lower melted continental mantle. The equilibrium temperature and pressure conditions of the xenoliths in Maguan area ranged from 900 °C to 1 105 °C and 1.29 MPa to 2.20 GPa (equivalent to 45 km - 71 km depth), respectively. A geothermal curve of the upper mantle in the Maguan area was consistent with the ocean-type upper-mantle geothermal curve. It revealed that the lithosphere mantle in Maguan area had a high value of thermal flow, indicating that the hot asthenosphere upwelled in the period of 0 - 16 Ma in eastern Asia and resulting in the east-west lithospheric extension in eastern Tibet and the whole eastern Asia.

Translated title of the contributionStudy on petrology and mineralogy of pyrolite xenolith in Maguan area, eastern Tibet
Original languageChinese
Pages (from-to)20-28
Number of pages9
JournalKuangwu Yanshi
Volume26
Issue number1
Publication statusPublished - Mar 2006
Externally publishedYes

Keywords

  • Eastern Tibet
  • Maguan
  • Mineral chemical composition
  • Petrology
  • Spinel-lherzolite xenoliths

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