北山—阿拉善地区二叠—三叠纪富碱侵入岩的岩石学特征

Petrology of Rich-Alkaline and Alkaline Intrusive Complexes in Beishan-Alxa Region

甘肃北山—内蒙古阿拉善地区发育有一套以正长岩、石英正长岩、霓辉正长岩、霓霞正长岩类为代表 ,包括碱性辉长岩、二长岩、石英二长岩、碱长花岗岩和碱性花岗岩等类岩石在内的富碱侵入体。本文总结了它们的空间分布、形成时代、产状、岩石组合和岩石化学特征 ;指出它们具有近东西向的分布特征 ,主体形成于二叠—三叠纪时期 ,具有富碱、碱性岩类的岩石化学特征 ,构成一条富碱侵入岩带 ;认为其时空分布特点与华北地台、塔里木地台北缘及邻区碱性岩带一致 。

A set of rich_alkaline and alkaline intrusive complexes occur in Beishan-Alxa region, Northwest China. There exist such types of rocks as syenite, quartz syenite, aegirine_augite syenite, nepheline syenites, monzonite, quartz monzonites, alkaline gabbro, alkaline_feldspar granites and alkaline granite.The distribution, formation time, modes of occurrence, associations and petrochemistry of these complexes are summed up in this paper. Formed in Permian to Triassic, these complexes stretch in east_west direction, they are rich_alkaline to alkaline in petrochemistry, making up a belt of rich_alkaline-alkaline rocks and serving as a part of the gigantic alkaline rock belt along the northern border and the neighboring area of the North China-Tarim platform.