新疆后造山碱性花岗岩的地质特征

新疆地区碱性花岗岩分布很广泛,可以划分出十条岩带,它们主要分布在古生代岛弧、弧后盆地及隆起区,与板块缝合线、深断裂密切相关,并与蛇绿岩和陆相火山岩相伴生。同位素年代测定表明,本区碱性花岗岩的形成是紧随造山运动之后发生的,属于后造山花岗岩。因此,它们形成时的构造环境、岩石化学成分、矿物组成及微量元素特征等均与非造山花岗岩(A 型花岗岩)有一定的区别。在一个地区有这么多后造山碱性花岗岩分布,国内外并不多见,这是新疆地质的一个特色。

Geological characteristics of the post-orogenic alkaline granites in Xinjiang

The alkaline granites are widely distributed in Xinjiang.They are situated in the island are,back arc basin and uplifted area,and related to suture line of plate and deep fault.The alkaline granites are associated usually with ophiolite and continental volcanic rock.and can be divided over 10 rock belts.It was indicated by the determine of isotopic ages that the intrusion of alkaline granite followed closely the orogenic movement,they are regarded as post-orogenic granite.So that,the tectonic environment during the forming of them,petrochemical composition,mineral constitutions and feature of trace elements are different from the anorogenic granite (A type of granite).It is a geological characteristics in Xinjiang.that so many alkahne granites concentrate here and it is not usually to see at home and abroad.