DOI: 10.3724/SP.J.1084.2013.00394

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


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

1 中国科学院“吉林陨石雨”联合考察组.吉林陨石雨的初步考察. 中国科学, 1977, (1): 38-47.

2 Van Schmus W R, Wood J A. A chemical-petrologic classification for the chondritic meteorites. Geochim Cosmochim Acta, 1967, 31(5): 747-765.

3 Sears D W, Grossman J N, Melcher C L, et al. Measuring metamorphic history of unequilibrated ordinary chondrites. Nature, 1980, 287(5785): 791-795.

4 Bischoff A. Meteorite classification and the definition of new chondrite classes as a result of successful meteorite search in hot and cold deserts. Planetary and Space Science, 2001, 49(8): 769-776.

5 王道德, 缪秉魁, 林杨挺, 等. 陨石的矿物-岩石学特征及其分类. 极地研究, 2005, 17(1): 45-72.

6 缪秉魁, 林杨挺, 欧阳自远, 等. 南极格罗夫山陨石岩石学特征Ⅱ: 平衡型普通球粒陨石. 极地研究, 2002, 14(4): 288-299.

7 缪秉魁, 王道德, 胡森, 等. 100块南极格罗夫山陨石的分类及其成对陨石的初步判别. 极地研究, 2008, 20(2): 141-152.

8 Sears D W G, Dodd R T. Overview and classification of meteorites//Meteorites and the Early Solar System. Tucson, AZ: University of Arizona Press, 1988: 3-31.

9 缪秉魁, 林杨挺, 欧阳自远, 等. 南极格罗夫山陨石岩石学特征Ⅰ: 非平衡L3型普通球粒陨石. 极地研究, 2002, 14(4): 276-287.

10 Brearley A J, Jones R H. Chondritic meteorites//Papike J J. Chondritic Meteorites in Planetary Materials. Reviews in Mineralogy, 1998, 36: 3-31.

11 Kita N T, Nagahara H, Togashi S, et al. A short duration of chondrule formation in the solar nebula: evidence from Al26 in Semarkona ferromagnesian chondrules. Geochimica et Cosmochimica Acta, 2000, 64(22): 3913-3922.

12 Dodd R T, Grover J E, Brown G E. Pyroxenes in the Shaw (L-7) chondrite. Geochimica et Cosmochimica Acta, 1975, 39(12): 1585-1586, IN1581-IN1582, 1587-1594.

13 Takeda H, Huston T J, Lipschutz M E. On the chondrite-achondrite transition: mineralogy and chemistry of Yamato74160 (LL7). Earth and Planetary Science Letters, 1984, 71(2): 329-339.

14 Stffler D, Keil K, Scott Edward R D. Shock metamorphism of ordinary chondrites. Geochimica et Cosmochimica Acta, 1991, 55(12): 3845-3867.

15 Wlotzka F. A weathering scale for the ordinary chondrites. Meteoritics, 1993, 28(3): 460-460.

16 Rubin A E. Kamacite and olivine in ordinary chondrites: Intergroup and intragroup relationships. Geochimica et Cosmochimica Acta, 1990, 54(5): 1217-1232.

17 Dominik B, Bussy F, Meisser N. The Chervettaz (L5) meteorite. Metroritics, 1994, 29(5): 696-697.

18 Lindsley D H. Pyroxene thermometry. American Mineralogist, 1983, 68(5-6): 477-493.

19 丁明伟, 张爱铖, 徐伟彪. 寺巷口普通球粒陨石的热变质和冲击变质历史研究. 天文学报, 2008, 49(1): 55-66.

20 林杨挺, 王道德, Kimura M. 南极GRV98002(L5)和GRV98004(H5)普通球粒陨石的热变质作用. 极地研究, 2002, 14(4): 266-275.

21 Taylor W R. An experimental test of some geothermometer and geobarometer formulations for upper mantle peridotites with application to the thermobarometry of fertile lherzolite and garnet websterite. Neues Jahrbuch für Mineralogie Abhandlungen, 1998, 172(2-3): 381-408.

22 Dodd R T. Meteorites: A Petrologic-Chemical Synthesis. Cambridge: Cambridge University Press, 1981: 364.