Marmo di Sevinèra

Rappresentazione e statuto

Colore CMYK

(28%,7%,0%,10%)

Colore RGB

R: 165 G: 215 B: 230

Rango

Formazione litostratigrafica

Uso

Unità in uso.

Status

termine informale

Nomenclatura

Deutsch

Sevinèra-Marmor

Français

Marbre de Sevinèra

Italiano

Marmo di Sevinèra

English

Sevinèra Marble

Origine del nome

Alpe di Sevinèra (TI), E Campo (Val Bavona)

Varianti storiche

Sevinèra marble (Matasci et al. 2011 p.262), Upper Jurassic marble

Descrizione

Potenza

Bis zu 30 m (Matasci et al. 2011).

Gerarchia e successione

Unità di rango inferiore

• White Member
• Yellow Member

Unità sovrastante

• Formazione dei Vanis

Unità sottostante

• Arenaria di Sevinèra

Età

Geomorfologia

• Tithoniano

Età alla base

• Oxfordiano

Geografia

Estensione geografica

Lepontin: Val Bavona.

Paleogeografia e tettonica

Termini generici

• Sambuco

Tipo di origine

• sedimentaria

Metamorfismo

monociclico

Referenze

Definizione

Matasci Battista, Epard Jean-Luc, Masson Henri (2011) : The Teggiolo zone: a key to the Helvetic–Penninic connection (stratigraphy and tectonics in the Val Bavona, Ticino, Central Alps). Swiss J. Geosci. 104, 257–283

p.262: 3.3.4 The Sevinèra marble

Calcitic marbles are a conspicuous constituent of the Teggiolo zone, although their distribution is discontinuous because they frequently disappear by erosion below the base of the third sedimentary cycle. They are well exposed on both banks of Val Bavona where their thickness can reach 30 m. Their lower limit with the Sevinèra sandstone is sharp. As they make nice outcrops at the same locality we call this marble formation the Sevinèra marble. It shows a gradual vertical evolution in composition and aspect and can conveniently be subdivided into two members:

1. The lower part has a characteristic yellowish to brownish color (‘‘yellow member’’). The base of this member is banded and consists in an alternation of cm or dm-thick beds of slightly impure limestones (10–20% of fine-grained quartz, feldspar, mica and dolomite), with more impure and more coarsely quartzic and micaceous limestones or calcschists (Fig. 3). It passes very progressively upwards, by attenuation of the bedding and increasing purity, to a more homogenous and massive, still yellowish limestone. The protolith of this sequence must have been an alternation of beds of more or less argillaceous limestones and marls, with decreasing upwards content in clay minerals and other fine-grained detritals.

2. The upper part is a very pure limestone (98% calcite). It is massive, homogeneous and white (‘‘white member’’).