The Earth’s early basaltic crust converted episodically into felsic TTG (tonalite-trondhjemite-granodiorite) crust by unknown tectonic processes. To contribute to the debate on the possible tectonic settings of TTGs, this article illustrates and explains migmatite structures of Meso- to Neoarchean TTG-amphibolite terrains in Arctic Fennoscandia. The Lake Inari and Rommaeno complexes in northern Finland and West Troms Complex in northern Norway consist of folded and banded TTG gneisses with abundant amphibolite enclaves. The terrains show migmatite structures generated by in situ and in-source melting of amphibolites and repeated metatexite-diatexite transitions that form infinite and boundless interconnected networks over vast areas. The aim of this article is to show that the TTGs of these terrains represent coalesced in situ and in-source neosomes of amphibolite protoliths and are not similar to granitoids sensu stricto generated by modern-style plate tectonics. The structures of the TTG-amphibolite associations of Arctic Fennoscandia suggest intracrustal differentiation by syn-anatectic partial melting of amphibolites in deep parts of a thick mafic crust.

地球早期的玄武质地壳通过未知的构造过程，转变成长英质的TTG（tonalite-trondhjeite-granodiorite）地壳。为了有助于就TTG可能的构造环境进行辩论，本文说明并解释了北极Fennoscandia中到新太古代TTG-闪石岩地形的辉石岩结构。芬兰北部的Inari湖和Rommaeno湖复合体以及挪威北部的西特罗姆斯复合体由折叠和带状的TTG片麻岩组成，并有丰富的闪石岩群。地形显示由原位闪石的源内熔化以及反复的变质岩-变质岩过渡，在广阔的区域上形成了无限且无限的互连网络。本文的目的是表明这些地形的TTG代表了合并的原位 和闪石原生质的源内新脂质体，与类固醇不相似 严格限制由现代板块构造产生。北极Fennoscandia的TTG-闪石结合体的结构表明，通过在厚铁镁质地壳深部的顺闪石的部分共熔使闪变作用，使壳内分化。