doi:

DOI: 10.3724/SP.J.1084.2013.00403

Chinese Journal of Polar Research (极地研究) 2013/25:4 PP.403-413

GEOCHEMISTRY OF SILICATES IN THE DONG UJIMQIN QI MESOSIDERITE AND THE IMPLICATIONS FOR ITS ORIGIN


Abstract:
The Dong Ujimqin Qi meteorite is a rare mesosiderite that fell in Inner Mongolia, China in 1995. It consists of intimately mixed metal-sulfide and silicates. Silicates in the mesosiderite are composed of clasts (mainly olivine and gabbro) with a gabbroic matrix. Petrographic and REE characteristics and major element compositions show that the olivine clasts, matrix olivine and gabbroic rocks (including gabbro clasts and gabbroic matrix) may have crystallized from different magmas. Olivine clasts, with high Mg contents, may be derived from the dunite mantle of a differentiated asteroid, whereas matrix olivine and gabbroic rocks may be from the same parental asteroid, e.g, the Vesta asteroid. An impact event may have led to the mixture of materials from these two asteroids. During the bombardment, temperature rose to 1 200-1 450℃ and the target basaltic and gabbroic rocks from the Vesta melted at the high temperature. Gabbroic rocks in the Dong Ujimqin Qi mesosiderite crystallized from the mixed melt. Olivine (both olivine clasts and matrix olivine), however, did not melt because the temperature was below its melting point. This model explains the disequilibrium between olivine clasts, matrix olivine and gabbroic rocks.

Key words:Dong Ujimqin Qi mesosiderite, olivine, gabbroic rocks, disequilibrium, origin

ReleaseDate:2014-07-21 16:59:42



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