摘要
对西秦岭礼县地区钾霞橄黄长质火山岩系中单斜辉石进行了矿物化学研究。斑晶相单斜辉石类型复杂 ,成分变化范围大 ,具有多源属性。基质相单斜辉石可以分为高Ti铝透辉石和含Ti透辉石两种基本类型 ,它们是同源岩浆演化结晶的产物 ,结晶顺序前者晚于后者。岩系中透辉石Ca (Mg ,Fe)Si2 O6 结晶过程中广泛存在着CaTiAl2 O6 分子替代 ,晚期熔体富Ti、Al贫Si、Mg ,熔体有向富Ti、Al、Fe、Na ,贫Mg、Si演化的趋势 ,在透辉石成分上表现为CaTiAl2 O6 和NaFe3+Si2 O6端员分子对Ca(Mg ,Fe)Si2 O6 的替代。本区基质相透辉石与世界上典型地区的钾霞橄黄长岩系的透辉石具有不同程度的可比性。
This paper has mainly studied chemical composition of clinopyroxenes from the kamafugitic series in Lixian County, West Qinling. The phenocrystal clinopyroxenes show complex types, complicated compositions, and multiple origins. The groundmass clinopyroxenes can be grouped into two pyroxene types: high_Ti aluminian diopside and Ti_bearing diopside which crystallized from the comagmatic melts. The substitution of CaTiAl 2O 6 for Ca(Mg, Fe)Si 2O 6 is common during the crystallization of diopsides, with the late melt rich in Ti and Al but poor in Si and Mg. Baicaoshan volcanic pipe is the product of an evolved magma with an evolutionary trend of Ti, Al, Fe, Na enrichment and Mg, Si depletion, which can be expressed by the substitution of CaTiAl 2O 6 and NaFe 3+ Si 2O 6 for Ca(Mg, Fe)Si 2O 6 during the crystallization process of diopsides. The diopsides of this area are comparable with diopsides from kamafugitic series in typical areas of the world, showing that bulk composition of kamafugitic rocks provides constraints on mineralogical composition and crystal lattice features.
出处
《岩石矿物学杂志》
CAS
CSCD
北大核心
2002年第3期251-264,共14页
Acta Petrologica et Mineralogica
基金
国家重点基础研究发展规划资助项目(G19980 4 0 80 0 )
关键词
礼县
新生代
钾霞橄黄长岩系
单斜辉石
矿物化学
West Qinling
Lixian County
Cenozoic
kamafugites
clinopyroxene
crystal chemistry
