Grundberg-Serie

Rappresentazione e statuto

Varianti storiche: Grundberg-Mulde (Bearth 1939, Bearth 1957), Grundberg series (Baudraz in: Steck et al. 2015)

Unità di rango inferiore

Geomorfologia

Età alla base

Revisione: 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.13: The basement of the Portjengrat nappe is overlain at the Grundberg above Saas-Grund by its autochthonous Mesozoic sedimentary sequence studied by Vincent Baudraz (personal communication). The Grundberg series starts with a Triassic sequence composed by up to 2 m of basal arkose, 2 m of dolomitic marble and cornieule (rauhwacke). 50 cm of a nodular calcschist and 1 m of a pure calcite marble, attributed to the Jurassic, separate the Triassic sequence from the probable Late Cretaceous sequence composed by 80 m of calcschist and 9 m of a sedimentary me´lange (wildflysch; Fig. 5). Basaltic dikes occur in both the gneissic basement and the sedimentary cover (marbles) of the Portjengrat unit in the Val Bognanco (Carrupt and Schlup 1998).