THE FEATURE OF THE REFLECTANCE SPECTRA OF UNEQUIUBRIUM QINGZHEN ENSTATITE CHONDRITE (EH3)
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摘要: 本文测定了清镇高铁群3型非平衡顽火辉石球粒陨石(EH3)的可见和近红外反射光谱, 发现其反射光谱既不同于显示Ni、Fe金属光谱特征的EH4(Abee)顽火辉石球粒陨石, 也不同于显示陨硫铁光谱特征的EH5型和EL6型平衡顽火辉石球粒陨石.清镇陨石独特的反射光谱特征可能是由于其铁纹石粒子表面存在光学厚度的吸积薄膜.吸积薄膜物质很可能是与铁纹石密切共生的陨硅磷镍铁矿, 也可能是它与硫化矿物的混合物.在清镇陨石中, 含吸积薄膜的铁纹石粒子可能具有很低的氧逸度, 它们极易被大气氧化而失去原有的反射光谱特征.文中讨论了EH3、EH4、EH5和EL6型顽火辉石球粒陨石具有不同反射光谱特征的宇宙化学机理.Abstract: The visible and near-infrared reflectance spectra. of unequilibrium Qingzhen enstatite chondrite (EH3) were measured. It is found that the reflectance spectra are different not only from those of Abee enstatite chondrite (EH4), showing Ni, Fe metal signature, but also from those of EH5 and EL6 enstatite chondrite, showing troilite feature. These unusual reflectance spectra of Qingzhen chondrite may originate from its metal grains which are coated with an accretionary layer of optical thickness. The layer is probably composed of perryite and/or mixture of perryite and sulfide. These metal grains probably have very low oxygen fugacity and are very easy to be oxidized by. air. The cosmochemical mechanism causing different reflectance spectra features of EH3, EH4, EH5 and EL6 enstatite chondrites are discussed.
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