Ofiolite della falda di Antrona

Representation and status

Color CMYK

(38%,0%,25%,37%)

Color RGB

R: 100 G: 160 B: 120

Rank

tectonically bounded lithostratigraphic unit

Validity

Unit is in Use

Status

informal term

Nomenclature

Deutsch

Ophiolith der Antrona-Decke

Français

Ophiolite de la nappe d'Antrona

Italiano

Ofiolite della falda di Antrona

English

Ophiolite of the Antrona nappe

Origin of the Name

Antronapiana (Italia)

Historical Variants

Ophiolite der Antrona-Anzasca-Mulde (Bearth 1939), Ophiolithe von Antrona-Bognanco = Ophiolithe der Zone von Antrona = Antronamulde (Bearth 1956), Antrona ophiolitic unit, Antrona ophiolite complex, Antrona mafic-ultrmafic complex (Colombi & Pfeifer 1986), unità ofiolitica di Antrona = ofioliti della Zona di Antrona = ofioliti mesozoiche di Antrona (Dal Piaz et al. 1992a), Antrona ophiolites (Keller 2004, Steck et al. 2015)

Description

Description

Serpentinite, Metabasalte und Metagabbros (mit Eklogitrelikten), sowie Kalkschiefern (ehemalige Sedimentbedeckung)

Hierarchy and sequence

Subordinate units

• Anfibolite della Val Loranco
• Eclogite di Andolla
• Serpentinite di Cisore
• Serpentinite della Punta della Forcola
• Peridotite degli Alpi di Cama

Upper boundary

Portjengrat-Einheit

Lower boundary

Monte-Rosa-Decke

Age

Age at top

• Kimmeridgian

Age at base

• Callovian

Dating Method

163.1 +/- 2.4 Ma, 158 +/-17 Ma and 155.6 +/- 2.1 Ma (U/Pb SHRIMP zircon ; Liati et al. 2005)

Palaenography and tectonic

Paleogeography

Piemont Basin

Tectonic unit (resp. main category)

• Antrona

Kind of protolith

• ophiolitic

Metamorphic facies

• greenschist facies (epizone)
• amphibolite facies
• eclogite facies

Note on metamorphism

HP-mtm (eclogite) + greenschist/amphibolite

References

Definition

Bill Markus, Masson Henri, Thélin Philippe (2001) : Low-grade metamorphism of the Gets nappe (Western Alps). Schweiz. Mineral. Petrogr. Mitt. 81, 229-237

The Antrona and Zermatt-Saas ophiolitic nappes are found in a structurally low position. They are affected by high-P metamorphism (eclogite facies) followed by greenschist to amphibolite grade metamorphism (Bearth, 1974; Dal Piaz, 1974b; Hunziker, 1974; Dal Piaz and Ernst, 1978; Colombi, 1989; Steck, 1989; Vannay and Allemann, 1990; Reinecke, 1991; Amato et al., 1999).