strati.ch - Lexique lithostratigraphique de la Suisse

Représentation et statut

Variantes historiques: Stelli-Zone (Bearth 1952, Bearth 1957b), Zona dello Stelli = zona di shear dello Stelli (Dal Piaz et al. 1992), Stellihorn shear zone (Pleuger et al. 2008), Stellihorn shear zone = Stelli mylonite zone (Steck et al. 2015)

Extension géographique: Schwarzberggrat, Mattmark, Stellihorn und Valle di Loranco.

Définition: Bearth Peter (1952) : Geologie und Petrographie des Monte Rosa. Beitr. Geol. Karte Schweiz N.F. 96, 118 Seiten

Révision: Steck Albrecht, Masson Henri, Robyr Martin (2015) : Tectonics of the Monte Rosa and surrounding nappes (Switzerland and Italy): Tertiary phases of subduction, thrusting and folding in the Pennine Alps. Swiss J. Geosc. 108/1, 3-34

p.10: Bearth (1952, 1957b) distinguished the about 25 km long and up to 2 km vide Alpine shear zone, the so-called ‘‘Stelli zone’’, named after the Stellihorn peak in the northern part of the Monte Rosa gneisses. It represents an Alpine mylonitised zone of ortho- and paragneisses with amphibolite boudins and rare kyanite and chloritoid bearing white schist. It is named according to Pleuger et al. (2008) the Stellihorn shear zone on the geological and structural maps (Fig. 3). It occupies the northern border of the Monte Rosa nappe between the Loranco valley, the Stellihorn and Mattmark, where it continues in a southern direction to the west of the Monte Moro pass and Macugnaga. Wetzel (1972) proposed a continuation of the Furgg series into Bearth’s Stelli zone. We are not convinced by this proposition. The gneisses with some amphibolite boudins are attributed to the old Monte Rosa basement. Wetzel and Bearth suggest that the Stelli mylonite zone separates a higher Monte Rosa from a lower Macugnaga sub-unit of the Monte Rosa nappe.