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魁歧花岗岩是我国东南沿海晶洞钾长花岗岩的代表性岩体。该岩体Rb—Sr等时线年龄为107m.y.,它是在南澳—长乐断裂挤压作用之后的拉张阶段侵位,以碱性花岗岩为主,伴有早期黑云母花岗岩的复式岩体。碱性花岗岩中长石为条纹长石,出现霓石和亚铁钠闪石。晶洞构造、花斑结构普遍发育。化学成分以富硅、碱,低铝、钙、镁为特征。岩石化学资料表明,魁歧花岗岩与共生的火山岩和其他花岗岩之间存在明显的同源关系,是同熔型岩浆分异演化晚期的产物。但该花岗岩以非造山、相对无水、富碱等特征类似于A型花岗岩,因此笔者建议将该类花岗岩列为同熔(A)型。
Kuiqi granite is the representative rock mass of the potash-bearing potash granite in the southeast coast of China. The Rb-Sr isochron age is 107m.y. It is emplaced in the extension stage after the extrusion of the Nanao-Changle fault, and is mainly composed of alkaline granites with complex biotite of early biotite granites body. Alkaline granite feldspar feldspar feldspar, appear niger and ferrous sodium amphibole. Geode structure, piebald structure generally developed. Chemical composition rich in silicon, alkali, low aluminum, calcium, magnesium is characterized. Petrochemical data show that Kuiqi granites have obvious homology with the symbiotic volcanic rocks and other granites, which is the product of the late differentiation and magmatic magmatic evolution. However, the granite is non-orogenic, relatively anhydrous, alkali-rich features similar to the A-type granite, so I propose this type of granite as the melt (A) type.