极地研究 ›› 2013, Vol. 25 ›› Issue (4): 394-402.DOI: 10.3724/SP.J.1084.2013.00394

• 研究论文 • 上一篇    下一篇

西宁陨石的岩石学特征及其类型划分

陈宏毅1,2  缪秉魁1,2 刘希军1,2 谢兰芳1,2 夏志鹏1,2  陈丽菲3   

  1.  
    1广西隐伏金属矿产勘查重点实验室,广西 桂林 541004;
    2桂林理工大学地球科学学院,广西 桂林 541004; 3广西区域地质调查研究院,广西 桂林 541004
  • 收稿日期:2013-03-27 修回日期:2013-04-18 出版日期:2013-12-30 发布日期:2013-12-30
  • 通讯作者: 缪秉魁
  • 基金资助:

    行星冲击产生的高温高压相变反应:月球火星陨石中后成合晶的研究

PETROLOGIC CHARACTERISTICS AND CLASSIFICATION OF THE XINING METEORITE

Chen Hongyi1,2, Miao Bingkui1,2, Liu Xijun1,2, Xie Lanfang1,2, Xia Zhipeng1,2, Chen Lifei3   

  1.  
    1Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, Guilin 541004, China;
    2College of Earth Sciences, Guilin University of Technology, Guilin 541004, China; 3Guangxi Regional Geological Survey Institute, Guilin 541004, China
  • Received:2013-03-27 Revised:2013-04-18 Online:2013-12-30 Published:2013-12-30

摘要: 西宁陨石具有典型的球粒结构,球粒轮廓依稀可辨-模糊,基质重结晶程度中-高等,次生斜长石粒度5-40μm,部分颗粒大于50μm。橄榄石和低钙辉石的化学成分均一:球粒中橄榄石Fa24.7-25.2,平均Fa24.9,相对标准偏差PMD值0.64%;低钙辉石Fs21.3-21.9 En 77.6-78.2 Wo 0.46-0.57,平均Fs21.5,Fs的PMD值0.84%。说明该陨石已达热力学平衡状态,为平衡型普通球粒陨石。根据该陨石结构构造特征、金属含量、矿物化学组成特征和热变质特征(平衡温度为778℃),西宁陨石被划分为L群普通球粒陨石,岩石类型为5型,但已开始向6型过渡。该陨石的冲击变质程度为S3,风化程度W0。陨石母体形成之后遭受了冲击变质作用和热变质作用,导致原始球粒破碎、脱玻化和基质重结晶。

关键词: 西宁陨石, 普通球粒陨石, 平衡型, L5, 降落陨石

Abstract: Xining meteorite has a typically chondritic texture. The matrix displays a moderate to high degree of recrystallization, most plagioclase grains are around 5-40μm and a few grains greater than 50μm in diameter . Chemical compositions of olivine and low-Ca pyroxene in Xining meteorite are homogeneous: eg. olivine (Fa 24.7-25.2,avg. Fa 24.9, PMD 0.64%); low-Ca pyroxene ( Fs 21.3-21.9, avg. Fs 21.5, PMD 0.84%; En 77.6-78.2, avg. En 78.6; Wo 0.46-0.57, avg. Wo 0.46). This feature indicates that olivine and low-Ca pyroxene in Xining meteorite are in thermodynamic equilibrium and Xining meteorite should belong to 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℃), Xining meteorite is a L5 ordinary chondrite and beginning to change a L6. The degrees of shock metamorphism and terrestrial weathering are S3 and W0, respectively. The parent body of Xining meteorite had suffered impact and thermal metamorphism, which had resulted in fragmentation of chondrules, devitrification of glass, and recrystallization of matrix.

Key words: Xining meteorite, Ordinary chondrite, Equilibrated type, L5, Meteorite fall