【摘要】 中国西北部天山石炭纪—早二叠世裂谷火山作用代表了一个新近被认可的大火成岩省。有人认为,在天山石炭纪火山岩系中发育有富Nb岛弧玄武岩、埃达克岩和高镁安山岩组合。然而,该岩石组合具有与典型富Nb岛弧玄武岩、埃达克岩和高镁安山岩不同的化学和同位素特点,表明其并非是岛弧岩石组合。这一推断的岛弧岩石组合实际上是大陆板内火山岩组合,由未遭受地壳混染、受到地壳轻微混染和遭受地壳强烈混染的大陆火山岩组成。更多还原

【Abstract】 The Tianshan Carboniferous-Early Permian rift-related volcanism in northwestern China represents a newly recognized large igneous province.It has been deemed that an assemblage of Nb-enriched arc basalt,adakite and high-Mg andesite occurred in the Tianshan Carboniferous volcanic successions.Divergent chemical and isotopic characteristics between this rock assemblage and the typical Nb-enriched arc basalts,adakites and high-Mg andesites reveal that the former is not arc related.This postulated arc-related assemblage is indeed an intracontinental volcanic assemblage that consists of crustally uncontaminated,less-contaminated and strongly contaminated continental volcanic rocks.更多还原