unità del (Pizzo) Osbarino

Rappresentazione e statuto

Definizione: Steck Albrecht, Della Torre F., Keller Franz, Pfeifer Hans-Rudolf, Hunziker Johannes, Masson Henri (2013) : Tectonics of the Lepontine Alps : ductile thrusting and folding in the deepest tetonic levels of the Central Alps. Swiss Journal of Geosciences, 106/3, 427-450

p.435: The Osbarino unit (named herein after the Pizzo Osbarino, located between the Toce and Isorno valleys, Fig. 2) is dominated by well foliated, leucocratic muscovite–biotite–granite gneiss. It may correspond to a southwestern continuation of the Bosco unit and continue farther west in the Valgrande gneiss. Schmidt and Preiswerk (1905) and Wieland (1966) distinguish this gneiss as the “Lebendun”-Zug and consider it with the Valgrande gneiss as the basement of the Lebendun conglomerates. We propose that the Valgrande gneiss represents the basement of the newly defined Pizzo del Vallone nappe of Mesozoic sediments (Carrupt 2002), whereas the Mesozoic Lebendun conglomerate and “schisti bruni” are considered as a rootless thrust sheet.