Banded amphibolites in the Alps: a new interpretation in relation to early Paleozoic peraluminous magmatism

Swiss Journal of Geosciences

Table 2 Square km and area percentages per main lithology from the different pre-Variscan gneiss units

	Aar Massif	Tavetsch Nappe	Gotthard Nappe	Silvretta Nappe	Ötztal Nappe	Strona-Ceneri Zone	Sum
Amphibolites	82 km² 7.3%	0.1 km² 0.1%	16 km² 3.2%	447 km² 22.0%	81 km² 1.7%	17 km² 2.0%	643 km² 7%
Orthogneisses	229 km² 20.3%	0 km² 0%	184 km² 37.1%	645 km² 31.8%	659 km² 14.2%	173 km² 20.0%	1890 km² 20%
Migmatites	622 km² 55.0%	18 km² 20.2%	66 km² 13.3%	0 km² 0%	0 km² 0%	0 km² 0%	706 km² 8%
Paragneisses	197 km² 17.4%	71 km² 79.7%	230 km² 46.4%	939 km² 46.2%	3892 km² 84.0%	675 km² 78.0%	6004 km² 65%
Sum	1130 km² 100%	89 km² 100%	496 km² 100%	2031 km² 100%	4632 km² 100%	865 km² 100%	9243 km² 100%

The data is plotted in the diagram of Fig. 6. Analysis is based on data taken from Zurbriggen (2015) for the Strona-Ceneri Zone, Geological Map of Switzerland, 1:500,000 (2008) for the Silvretta Nappe, Egger et al. (1999) for the Ötztal Nappe, and Berger et al. (2016) for the Aar Massif, Tavetsch Nappe and Gotthard Nappe. Note: In case of the Aar Massif, the Gärsthorn Gneiss Complex was classified as orthogneiss, Guttanen and Lötschental Gneiss Complexes as paragneisses, and the Ofenhorn-Stampfhorn, Erstfeld, Innertkirchen-Lauterbrunnen and Massa Gneiss Complexes as migmatites