福建魁岐花岗岩的岩石学和地球化学特征及成因探讨

PETROLOGY,GEOCHEMISTRY AND GENESIS OF KUIQI GRANITE BATHOLITH

在浙闽粤沿海中生代断陷活动带内，政和一大埔深断裂以东沿海地区，存在着一条绵延五百余公里、宽约六十公里、呈NNE向分布的晶洞钾长花岗岩带。福建魁岐花岗岩位于该岩带北部，是该带中具有代表性的岩体。鉴于此花岗岩所具有的特殊意义，本文试图通过对魁岐花岗岩的岩石学和地球化学等特征的综合研究，来探讨岩石成因归属问题。

The Kuiqi granite batholith outcrops in the vicinity of Fuzhou City, Fujian Pro-vince and constitutes one of the typical alkali granitic complexes in the 'Belt of Mia-rolitic Granites'' extending along the southeast coast of China. The complex is believed to have been emplaced at higher levels of the crust in a tensional fault environment. Petrographically it is composed mainly of aegirine-arfvedsonite granites with early bio-tite granites scattered. Miarolitie structure and granophyric texture are commonly ob-served. The Rb-Sr isochron age of the complex is 107.65 m.y. Both petrological and petrochemical studies show that the Kuiqi granite is of A-type. Data on chemical com-position, REE pattern and transition elements reveal that there is a close genetic con-nection between granites and associated volcanic rocks. Thus, syntexis-type (I-type) granite, A-type granite and volcanic rocks form a cogenetic 'trinity', in which the A-type granite is usually the latest member of the volcanic-intrusive serj.es.