前寒武纪科马提岩研究概况

Research Survey of Precambrian Komatiite

科马提岩是前寒武纪绿岩的重要组成部分,对探讨前寒武纪地球演化历史、壳—幔演化及岩石成因等方面有着重要的意义。科马提岩来源于地幔的镁铁质、超镁铁质火山熔岩,具有流动熔岩的结构构造,其化学成分表现为Si O246%-53%,Mg O〉9%,Ca O/Al2O3〉1,K2O〈0.9%,Ti O2〈0.9%,F/F＋M比值低,Ti O2含量低,Mg O、Ni、Cr含量高。且不同产地的科马提岩具有不同的化学组成,主要分为贫铝科马提岩、富铝科马提岩、钛富集型科马提岩与镁铁质富镁的科马提岩。目前主流的成因模式为Jarvis G.T,Campbell I.H等先后提出的热地幔柱模式,认为科马提岩为地幔柱引起的高温熔融形成的。

Komatiite is an important component of the Precambrian greenstone, that has important significance to explore the Precambrian earth evolution history, crust-mantle evolution and rock formation, etc. Komatiite is derived from the mantle mafic ,super mafic volcanic lava,and has lava flow structure. The chemical composition expression SIO246% ~ 53%, MgO 〉 13 9% ,CaO/Al2O3 〉 1 ,K2O〈0.9% ,TiO2 〈0.9% ,F/F ＋ M ratio is low,low content of TiO2 ,high content of MgO style, Ni and Cr. Komatiite in different regions has different chemical composition, mainly divided into poor aluminum komatiite, rich aluminum komatiite, enrichment of titanium type komatiite and mafic rich magnesium komatiite. The cause mode of the current mainstream, is by Jarvis G. T, Campbell I. H successively put forward the hot mantle plume model, such as consider komatiite for mantle plume caused by high temperature melt.