Fig. 5

Three models for the structural relations between the Sambuco, Maggia, Antigorio and Simano units in the region of Peccia and Fusio in the upper Maggia valley. a On the Tektonische Karte der Schweiz (2005), the Sambuco and Maggia units are connected by a strip of gneisses and the Campolungo Mesozoic sediments continue in the zone of Pertusio. This model is contrary to Keller et al. (1980) and new fieldwork. b In this model it is suggested that the Alpigia granodiorite and tonalite forms an integral part of the Maggia nappe. The Alpigia granodiorite and tonalite are similar to the Matorello and Cocco intrusions (Grütter and Preiswerk in Niggli et al. 1936). The textures of this granitoids are characterized by biotite aggregates also typical for the Matorello and Cocco intrusions. c On the model proposed in this paper (Fig. 2) the Maggia and Sambuco units represent two klippes of a single Magga nappe. The two triple points between the Antigorio, Sambuco and Simano units to the north and between the Antigorio, Maggia and Simano units to the south may be explained by a younger overthrust of the Maggia–Sambuco son the older Antigorio and Simano nappes. In any case, the Antigorio basement with its Helvetic Mesozoic cover sequence (Teggiolo zone) and the Simano basement with its Penninic Mesozoic sediments (Campolungo zone) are different and the structural relations of the Antigorio and Simano nappes are in all three models open to question. Model c is our preferred interpretation of the Alpine structures of the Peccia and Fusio region, but model b is also possible and cannot be excluded