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首页 > 中国极地考察知识库 > 成果信息库 > 已审查 Shock effects and the classification of H-chondrites from the Grove Mountains, East Antarctica: Implications for the shock history of H-chondrite parent bodies

Shock effects and the classification of H-chondrites from the Grove Mountains, East Antarctica: Implications for the shock history of H-chondrite parent bodies

【标题】Shock effects and the classification of H-chondrites from the Grove Mountains, East Antarctica: Implications for the shock history of H-chondrite parent bodies

【Title】Shock effects and the classification of H-chondrites from the Grove Mountains, East Antarctica: Implications for the shock history of H-chondrite parent bodies

【作者】 王保华; 缪秉魁

【Author】 Wang BaoHua ; Miao Bingkui

【期刊】极地研究

【Journal】

【期刊年份】2011

【卷】22

【期】2

【关键词】 Ordinary chondrite; Grove Mountains; H-chondrite; shock stage; Wadsleyite

【Keywords】 Ordinary chondrite; Grove Mountains; H-chondrite; shock stage; Wadsleyite

【摘要】The shock metamorphism of 47 H group chondrites (H-chondrites) from the Grove Mountains including undulatory extinction, planar fractures, mosaic extinction, shock veins and pockets, and dendritic eutectic metal-sulfide, is observed through optical microscope. The textures and assemblages of shock veins in these H-chondrites are examined by the scanning electron microscope. Based on observations of the above shock effects, the shock stages of the 47 H-chondrites are classified into S1(5), S2(19), S3(14), S4(8) and S5(1). Of these H-chondrites, GRV 022469 has the highest(S5) shock stage. The comparison of shock stages in these H-chondrites with L group chondrites(L-chondrites) indicates that the shock metamorphism of H-chondrites is relatively low (except for GRV 022469, they are all lower than S5). A scenario for the history of the H-chondrite parent body is proposed that suggests the duration of the shock events in the H-chondrite parent bodies was much shorter than those in L-chondrite parent bodies. Also, the pressure may have been released more quickly, and consequently, the high-pressure phases should be easily preserved. However, the parent bodies of the H-chondrites may have been exposed to high temperatures for a longer time after the shock event, so the high-pressure phases formed by solid transformation might have retro-metamorphosed to low-pressure ones; its peak pressure is estimated to be less than 15 GPa. Wadsleyite was found in a shock vein in GRV022469, as confirmed by the Raman spectrometer. Petrological and mineralogical characteristics support the idea that the wadsleyite was formed by solid-state transformation.

【Abstract】The shock metamorphism of 47 H group chondrites (H-chondrites) from the Grove Mountains including undulatory extinction, planar fractures, mosaic extinction, shock veins and pockets, and dendritic eutectic metal-sulfide, is observed through optical microscope. The textures and assemblages of shock veins in these H-chondrites are examined by the scanning electron microscope. Based on observations of the above shock effects, the shock stages of the 47 H-chondrites are classified into S1(5), S2(19), S3(14), S4(8) and S5(1). Of these H-chondrites, GRV 022469 has the highest(S5) shock stage. The comparison of shock stages in these H-chondrites with L group chondrites(L-chondrites) indicates that the shock metamorphism of H-chondrites is relatively low (except for GRV 022469, they are all lower than S5). A scenario for the history of the H-chondrite parent body is proposed that suggests the duration of the shock events in the H-chondrite parent bodies was much shorter than those in L-chondrite parent bodies. Also, the pressure may have been released more quickly, and consequently, the high-pressure phases should be easily preserved. However, the parent bodies of the H-chondrites may have been exposed to high temperatures for a longer time after the shock event, so the high-pressure phases formed by solid transformation might have retro-metamorphosed to low-pressure ones; its peak pressure is estimated to be less than 15 GPa. Wadsleyite was found in a shock vein in GRV022469, as confirmed by the Raman spectrometer. Petrological and mineralogical characteristics support the idea that the wadsleyite was formed by solid-state transformation.

【基金/项目】 南极陨石冲击变质作用研究 ; 我国南极不同化学群碳质球粒陨石的对比研究:早期太阳星云的演化特征及其不均一性

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