内蒙古大兴安岭北部新元古代花岗岩岩石地球化学特征及构造意义

大兴安岭北部发育有大量的新元古代花岗岩，通过开展1/25万莫尔道嘎-奇乾幅区域地质调查工作，将其划分为3个构造岩浆阶段，共7个填图单元.岩石组合及岩石地球化学特征的研究表明，早期的中基性杂岩-花岗闪长岩系列岩浆主要来源于上地幔或下地壳，是俯冲作用和壳幔相互作用的产物；中期似斑状钾长花岗岩-二长花岗岩系列岩浆来源于下地壳，是碰撞造山作用的产物；晚期正长岩主要来自下地壳，形成于造山晚期的伸展体制.整个新元古代岩浆岩的发展演化过程客观地反映了大兴安岭北部西伯利亚板块南缘的运动学特征.

GEOCHEMICAL CHARACTERISTICS AND TECTONIC SIGNIFICANCE OF THE NEOPROTEROZOIC GRANITES IN NORTHERN DAXINGANLING, INNER MONGOLIA

The well-developed Neoproterozoic granites,broadly distributed in Northern Daxinganling,Inner Mongolia,were formed in three tectono-magmatic stages,with seven rock units.Study on the rock assemblage and geochemistry of the granites shows that,the magma of intermediate-basic complex-granodiorite series in the early stage was derived mainly from upper mantle or lower crust,as the result of subduction and crust-mantle interaction.The magma of porphyritic moyite-monzogranite series in the middle stage mainly originated from the lower crust,being the product of collision-orogeny.The magma of syenite series in the late stage,mainly from the lower crust,was formed in the extensional system in the later of orogenic period.The development and evolution of the Neoproterozoic magmatic rocks has reflected the dynamic characteristics of the south margin of Siberian plate in Northern Daxinganling.