A型花岗岩研究现状及其述评

Present situation of researches on A-type granites:a review

在20多年的研究历史中,随着同位素测年和示踪技术的不断完善,地质学家对地幔和壳幔相互作用的认识愈来愈深刻。同样,随着研究案例的日积月累,对A型花岗岩的认识也在不断更新。现在,人们所讨论的A型花岗岩已经不再局限于狭义的花岗岩,事实上已经扩大到花岗质岩类(如闪长岩和辉长岩)甚至喷出岩(流纹岩、流纹-安山岩),其识别标志像埃达克岩(adakite)那样越来越依赖于主元素、微量元素和同位素等地球化学指纹,其物源的多样性和成因的多种模式得到多种同位素联合示踪研究结果的不断支持,但其形成时的构造环境仍然以伸展体制为主。

With the continuous improvement of the isotopic and tracing technologies for dating rocks, geologists have gained increasingly deepened understanding of the mantle and the interaction between the crust and the mantle in the past twenty years. Correspondingly, the knowledge of the A-type granite has been continually renewed. At present, just like adakite, A-type granites have covered granitoids （including their extrusive rocks such as rhyolite and rhyoandesite）. The identification of A-type granites depends increasingly upon their major and trace elements as well as their isotope characteristics. Although A-type granites have diverse sources and genetic models, their tectonic setting remains mainly dominated by the extensional system.