片内无根褶皱是变质岩系中分布广泛的一种小型构造,它的存在是面理置换的重要判据之一(特纳等,1963),对于认识区域性面理的成因,恢复区域构造具有重要意义。本文对四川北部南江上两地区火地垭群中片内无根褶皱进行了研究。 一、火地垭群中的片内无根褶皱 火地垭群广泛出露于杨子地台北缘的米仓山变质带。它是一套变质的火山-沉积岩系,组成一系列走向北东-北东东的复背斜、复向斜,为晋宁期中酸性岩浆岩侵入,并被震 On-chip root folds are a type of small structure widely distributed in the metamorphic rocks. Its existence is one of the most important criteria for face replacement (Turner et al., 1963). For the reason of regional physiognomy, the recovery area Construction is of great importance. In this paper, the root-less folds in the Huo-di-hua group in the two areas of Nanjiang in northern Sichuan were studied. First, the fire in the group of root-free film within the root fold Huoji group widely exposed in the northern margin of the Yangzi platform Micangshan metamorphic belt. It is a set of metamorphic volcano-sedimentary rocks that make up a series of anticlinal anticlines and synclinosils that go to NE-NE and intrude into acidic magmatic rocks in the Jinning Period,