摘要
通过对34个取自金伯利岩管中的粗晶镁铝榴石及碱性玄武岩中镁铝榴石巨晶样品的红外光谱分析发现,金伯利岩中部分镁铝榴石粗晶含有结构水,但不同颗粒之间含量差异很大,含量较高者约0.07wt%,而所研究的碱性玄武岩中的镁铝榴石不含结构水。分析发现,结构水在同一样品内分布基本均匀。在红外光谱3800—3500cm^(-1)波长范围内,分别记录到三峰谱和单峰谱两种类型,其中位于3570cm^(-1)±的吸收峰峰位明显受镁铝榴石结构中八配位阳离子(Mg^(2+)、Fe^(2+))影响,而六配位阳离子(Cr^(3+)、Al^(3+))的影响不明显。结构水在镁铝榴石晶格中的存在形式是多样的。
34 pyrope samples from the Liaoning No. 50 diamondiferous kimberlitepipe and the Kuandian alkali basalt in Liaoning Province were carefullyanalyzed by using infrared spectroscopy and electron microprobe. It has been found that some coarse pyrope crystals from kimberlite have constitutionalwater, Whose content is uniform in a grain but varies remarkably from grainto grain: the estimated content is about 0.07 % in a comparativelywater-rich sample, whereas no constitutional water has been found in sixpyrope samples from alkali basalt. Two kinds of spectra were recorded, i. e.three-peak band and one-peak band, in which the frequency of The band near3570 cm^1 is obviously controlled by Mg^2+ and Fe^2+ in octahedral coordina-tion but has little to do with six-coordinated Cr^3+ and AI^3+. The model(H_4O_4)~4- =(SiO_4)~4- in pyrope lattice is still problematic in interpreting allthe experimental xesults: in addition to(H_4O_4)~4-, other substitute forms axealso likely to exist.
出处
《岩石矿物学杂志》
CAS
CSCD
1992年第1期61-69,共9页
Acta Petrologica et Mineralogica
关键词
镁铝榴石
结构水
红外光谱
Infrared spectrum
constitutional water
kimberlite
alkali basalt
