女山和盘石山橄榄岩包体中的水: 红外光谱研究

运用傅立叶变换红外光谱技术对来自安徽女山新生代碧玄岩中的6个和江苏盘石山新生代玄武岩中的3个名义上“干”橄榄岩包体中的矿物进行了观察。结果显示:单斜辉石和斜方辉石普遍含有微量的结构水,以OH^-的形式赋存;除1个女山包体外,其余的橄榄石均未探测到结构水;女山1个石榴石橄榄岩中的石榴石未能探测到结构水。单斜辉石中结构水含量>斜方辉石>>橄榄石(石榴石)。结合文献中的资料来看,岩石圈地幔中水的分布可能既具有大尺度不均一性,又具有小尺度不均一性,可能并不具有明显的垂向分带。

WATER IN PERIDOTITE XENOLITHS FROM NUSHAN AND PANSHISHAN: FTIR STUDY

Minerals in nominally “dry” peridotite xenoliths from Cenozoic basanites from Nushan, Anhui (six samples) and Panshishan, Jiangsu (three samples) have been investigated by fourier transform infrared spectroscopy (FTIR). The results demonstrated that clinopyroxenes and orthopyroxenes commonly contained trace amount of structural water as hydroxyl, only one olivine contained structural hydroxyl, garnet from one garnet-lherzolite from Nushan had not structural water. The water content of clinopyroxene was higher than that of orthopyroxene, and far higher than that of olivine (garnet). Combining the previously published data, it was suggested that both large scale and small scale heterogeneities of the water distributions possibly occured in the lithospheric mantle, and the lithospheric mantle did not show vertical zoning of water distributions.