【摘要】 在东秦岭北部 ,富碱侵入岩的侵位与空间分布受同一个区域构造带 (华北陆块南缘 )控制 ,构成一个区域性的富碱岩浆岩带。根据岩石学和岩石化学研究 ,岩石类型主要分为三大类 :(1)碱性岩类 ,即含有似长石或碱性暗色矿物的正长岩类 ;(2 )碱性花岗岩类 ,包括钠铁闪石花岗岩及孪生的钾长花岗岩类 ;(3)石英正长岩类 ,包括碱性长石为主的石英正长岩、英碱正长岩和花岗正长 (斑 )岩类。根据富碱岩浆岩带的岩石化学特征 ,自北而南可以划分为三个亚带 :北部碱性岩亚带 ,以 Si O2 饱和而 Al2 O3不饱和出现碱性暗色矿物为特征 ;中部碱性花岗岩亚带 ,以 Si O2 强饱和而 Al2 O3不饱和出现碱性暗色矿物和大量石英为特征 ;南部石英正长岩亚带 ,以 Si O2 和 Al2 O3都饱和但 Ca O强烈亏损 ,缺乏 Ca质斜长石 ,出现碱性长石占长石总量的绝对优势 (一般 >95 % )为特征。三个亚带富碱岩浆在化学成分方面虽有差异 ,但共同具有富碱高钾特征 ,AL K=10～ 15 ,K2 O含量范围 5 %～ 15 % ,K2 O/ Na2 O=1.2 6～ 8.30。更多还原

【Abstract】 The alkali-rich intrusive rocks are mainly located in Luonan- Lushi- Queshan area in the northern part of East Qinling, central China, and their occurrences are controlled by a regional tectonic zone. Based upon systematic petrographic a nd geochemical studies, the intrusive rocks are divided into three types: (1) Th e alkaline rock type, that is syenitoid containing foid or alkaline dark mineral s; (2) The alkaline granitoid including arfredsonite granite and assemblage moyi te; (3) quartz syenite including quartz syenite, nordmarkite and granosyenite(po rphyry), which took alkaline feldspars as the dominate factors. All these rocks consisted an alkali-rich magmatic rock belt in space, that can be divided into three subzones according to the features of petrochemistry from north to south: the northern subzone of alkaline rock, middle subzone of alkaline granitoid and southern subzone of quartz syenite (porphyry). The three subzones of alkali-ric h intrusive rocks belong to the same category of the high-K, ALK=10~15, K 2O=5 %~15%, K 2O/Na 2O=1.26~8.30.更多还原