长白山天池火山岩浆演化——来自主矿物成分的证据

长白山天池火山岩的主要矿物成分为橄榄石、辉石、长石和铁钛氧化物，经电子探针测试，其成分变化特征明显，自造盾阶段一造锥阶段一全新世喷发，橄榄石中铁含量增加，一直达到铁橄榄石的端元组分；单斜辉石中铁质和钠质含量增加；长石则从基性的拉长石向含钾、钠渐高的歪长石和透长石演化；铁钛氧化物含量则明显减少。三阶段斑晶矿物成分的变化反映了天池火山近200万年来岩浆演化的完整系列，符合分离结晶作用的演化趋势。

Magma evolution of Changbaishan Tianchi volcano:Evidences from the main phenocrystal minerals

The main phenocrysts of Changbaishan Tianchi volcanic rocks were olivines, pyroxenes, feldspars and Ti-Fe oxides,which had clear characteristics of components evolution by electron microprobe analysis. From shield-forming stage, cone-forming stageto Holocene eruptions, the content of iron in olivines kept increasing till it almost reached the end-member of fayalite; iron and sodiumcontents also increased in clinopyroxene. In the meantime, feldspars evolved from labradorite to anorthoclase and sanidine which hadmore potassium and sodium, and the contents of Fe-Ti oxides in rocks were reduced cleary. The evolution of phenocrysts in threestages of Tianchi volcanic rocks reflected the complete series of Tianchi magma evolution in 2 Ma, which was in conformity with theevolution tide of fractional crystallization.