doi:

DOI: 10.3724/SP.J.1084.2013.00394

Chinese Journal of Polar Research (极地研究) 2013/25:4 PP.394-402

PETROLOGIC CHARACTERISTICS AND CLASSIFICATION OF THE XINING METEORITE


Abstract:
The Xining meteorite has a typically chondritic texture. The matrix displays a moderate to high degree of recrystallization. Most plagioclase grains have a diameter of around 5-40 μm with a few grains greater than 50 μm. The chemical compositions of olivine and low-Ca pyroxene in the Xining meteorite are homogeneous: e.g., olivine (Fa24.7-25.2, avg. Fa24.9, PMD 0.64%); low-Ca pyroxene (Fs21.3-21.9, avg. Fs21.5, PMD 0.84%; En77.6-78.2, avg. En78.6; Wo0.46-0.57, avg. Wo0.46). This feature indicates that the olivine and low-Ca pyroxene in the Xining meteorite are in thermodynamic equilibrium and the Xining meteorite should be classified as an equilibrated ordinary chondrite. Based on the textural characteristics, metal abundance, chemical composition of silicate minerals and thermal metamorphic characteristics (the equilibrium temperature is 778℃), the Xining meteorite is classed as an L5 ordinary chondrite that is beginning to change to an L6. The degrees of shock metamorphism and terrestrial weathering are S3 and W0, respectively. The parent body of the Xining meteorite suffered impact and thermal metamorphism, which resulted in fragmentation of chondrules, devitrification of glass, and recrystallization of the matrix.

Key words:Xining meteorite, ordinary chondrite, equilibrated type, L5, meteorite fall

ReleaseDate:2014-07-21 16:59:41



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