【摘要】 <正> 长白山脉的主峰白头山是我国最年轻的火山之一。白头山碱性火山岩是中、晚更新世和全新世二期火山喷发的产物(刘嘉麒,1983)。第一期喷发以溢出熔岩为特征,熔岩主要是石英粗面岩、石英碱性粗面岩、碱流岩,形成了白头山火山锥的主体。全新世的喷发产物主要为浮岩和熔凝灰岩,其化学成分与碱流岩相似(郑祥身,1983)。岩石学和岩石化学资料表明,在岩浆演化的最后阶段,依次出现的是石英碱性粗面岩和碱流岩等碱性岩石(郑祥更多还原

【Abstract】 In the evolving stage of the alkaline magma from Baitoushan volcano, the alkaline rocks, alkali-quartz-trachyte and pantellerite, had appeared in proper order, of which there are many solid-state inclusions in the phenocrysts, especially in anorthoclase and quartz. Three kinds of inclusions from pantellerite have been analysed with an electron microprobe.The different associations of several distinguishable phases and the different compositions in distinct inclusions show a heterogeneity of melt. The composition of solid inclusions could have been changed by the precipitation of host mineral on the inclusion’s wall and the crystallization of daughter crystal, so that they probably represent only the composition of a residual melt when a phenocryst phase stopped crystallizing rather than that of a parent magma during initial crystallization. These compositions provide some information about the evolving trend of a magma.The result from studing the solid inclusion’s composition, which is consistent with the conclusion from petrological and petrochemical evidences, suggests that the fractional crystallization of anorthoclases controls the evolution of Baitoushan alkaline melt from alkali-quartz-trachyte to pantellerite, and the acmite-augites have only a little effect on the evolution.更多还原