Graphitische Einheit (der Camosci-Decke)

Darstellung und Status

Farbe CMYK

(0%,0%,0%,100%)

Rang

lithostratigraphische Formation

Gebrauch

Element ist in Gebrauch

Nomenklatur

Deutsch

Graphitische Einheit (der Camosci-Decke)

Français

Unité graphitique (de la nappe des Camosci)

Italiano

Unità grafitica (della falda dei Camosci)

English

Graphitic unit (of the Camosci nappe)

Historische Varianten

black phyllitic schists + calcschists complex (Bianchi et al. 1998), Graphitic unit = Toarcian-Aalenian (Carrupt 2003)

Beschreibung

Mächtigkeit

Environ 75 m (Carrupt 2003 Fig.2.4)

Hierarchie und Abfolge

Untergeordnete Einheiten

• Detritische Einheit (der Camosci-Decke)

Alter

Alter Top

• Aalénien

Alter Basis

• Toarcien

Datierungsmethode

Ennoyement de la plateforme / black shales au Toarcien-Aalénien (Carrupt 2003).

Referenzen

Erstdefinition

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: Graphitic unit: is characterized by important lateral variations of facies (Fig.10.2). The clearest succession is found in the western part of the nappe. A black graphitic micaschists (metashale, see microscopic description in paragraph III.4) containing porphyroblasts of garnets, immediately follows the Calcareous unit; the contact is clear-cut. It may contain rare thin levels of a calcareous graphitic micaschist (metamarls). Bianchi et al. (1998) found various heavily recristallized bioclasts in the black micaschist. The eastern part is more complex. A calcareous graphitic micaschist (metamarls, see microscopic description in paragraph III.4) containing porphyroblasts of plagioclase or epidote overlies the Calcareous unit. The contact is gradual: thin levels (3 cm) of calcareous micaschist alternate with the calcitic marble; the latter becomes thinner upsection, whereas the calcareous micaschist thickens. Some graded bedding can be observed, indicating the local polarity (Fig.2.4). Up sequence, thin levels of black micaschist are interbedded within the calcareous micaschist. The lateral transition between the western and the eastern part of the Graphitic unit is made over less than 2 m. A very hard and dark 50 cm-thick rock composed of graphite (50%), carbonate (29%), muscovite (12%), opaque (8%) and some accessory minerals, represents the transitional stage between the calcareous micaschist and the black micaschist.