strati.ch - Lessico lithostratigrafico della Svizzera

Rappresentazione e statuto

Varianti storiche: Marbles + Quartzites (Bianchi et al. 1998), Calcareous unit = Liassic (Carrupt 2003)

Unità sovrastante

Geomorfologia

Età alla base

Metodo di datazione: Analogies de faciès : présence de deux niveaux quartzitiques (Lotharingien et Domérien) (Carrupt 2003).

Definizione: Carrupt Elisabeth (2003) : New stratigraphic, structural and geochemical data from the Val Formazza - Binntal area (Central Alps). Mémoires de Géologie (Lausanne) 41, 103 p.

p.17: Calcareous unit: the contact with the underlying Dolomitic unit is either gradual or clear-cut. Whenever in contact with the lustrous micaschist (rare), the contact is clear-cut. But when it is in contact with the metasandstone, a transitional passage from the metasandstone to a quartzitic calcitic marble is observed over 5 metres. Upsection the marble becomes gradually purer until it gives way to a pure calcareous recrystallised marble. The latter is laterally discontinous but may reach 20 metres in thickness at its most central part. The detritic fraction (quartz, dolomite, micas) then increases again. Most of the marbles contain up to 20% of quartz and about 10% of phyllosilicates. A quartzitic level follows which gradually interfingers with subordinated thin levels of calcitic marble. These marble interbeds progressively thicken and dominate upon the quartzitic layers. The subordinated layers, the quartzite as well as the calcitic marble, are often boudinaged probably due to alpine deformations. A quartzitic calcitic marble surmounts this series: the latter may contain discontinuous thin levels of quartzitic and dolomitic metasandstone. A 1 m-thick discontinuous quartzitic level ends this Calcareous unit.