«Unità del Lucomagno»

Rappresentazione e statuto

Colore CMYK

N/A

Colore RGB

R: 241 G: 239 B: 237

Rango

falda

Uso

Unità in uso.

Status

termine informale

Discussione del statuto

Nomenclatura

Deutsch

«Lucomagno-Einheit»

Français

«Unité du Lukmanier»

Italiano

«Unità del Lucomagno»

English

«Lucomagno Unit»

Origine del nome

Passo del Lucomagno (TI)

Varianti storiche

Lucomagnomassiv (Jenny et al. 1923), Lucomagnodecke (Bosshard 1925), Lucomagno-Decke (Gansser & Dal Vesco 1964), Ricoprimento Lucomagno (Bianconi 1971), Lucomagno-Masse (Büchi & Trümpy 1976), falda del Lucomagno, Lucomagno unit (Böhm et al. 1996), Lucomagno Nappe (Berger et al. 2017)

Descrizione

Descrizione

Involucro paragneissico a misto della falda Leventina-Lucomagno (metapelitischer Paragneis, gebänderter Gneis, Augengneis).

Gerarchia e successione

Unità di rango inferiore

• zona del (Pizzo) Molare
• Cristallino di Prato-Cornone

Età

Geomorfologia

• Mesozoico

Età alla base

• Precambriano

Paleogeografia e tettonica

Paleogeografia

placca continentale europea

Termini generici

• Lucomagno

Referenze

Revisione

Gouffon Yves (Editor) (2024) : Tectonic Map of Switzerland 1:500000, Explanatory notes. Federal Office of Topography swisstopo, Wabern

p.50: The Leventina-Lucomagno Nappe is the lowest unit of the Ticino Culmination. The lower part of the nappe (“Leventina Unit”) is made up of several orthogneisses forming a deformed Late Variscan magmatic edifice composed of several magmatic pulses. Along the northeastern flank of the Valle Leventina, the Leventina orthogneisses are covered by a thick stack of paragneisses and micaschists (“Lucomagno Unit”). Along this boundary, sparse quartzitic gneisses (“roof quartzites”) were interpreted as being Mesozoic in age by several authors and hence used to discriminate between a “Leventina Nappe” and a “Lucomagno Nappe”. However, these quartz-rich horizons above the orthogneisses form metasomatically altered zones – in places sheared – and cannot be considered as Mesozoic metasediments (Rütti et al. 2005; see Fig. 7). The “Lucomagno Unit” can therefore be regarded as a pre-Alpine sedimentary shell of the Leventina magmatic edifice deformed during the Alpine orogeny. Quartzitic horizons, similar to those mentioned above, also occur where the Simano Nappe directly overlies the Leventina orthogneisses. The northern part of this nappe contact is often characterized by a mylonitic band (Rütti et al. 2005 and ref. therein). To the south, this mylonitic shear zone dissipates within the Leventina orthogneisses in an anastomosing network of shear bands (Fig. 7). There, the upper limit of the Leventina-Lucomagno Nappe is difficult to trace since paragneiss and calcsilicate lenses – traditionally used to trace the tectonic contact – are in fact deformed xenoliths within the Leventina orthogneisses.
Remnants of Triassic rocks crop out around the frontal part of the Leventina-Lucomagno Nappe, although for some of them it is not clear whether they belong to the Leventina-Lucomagno Nappe or to the adjacent units. Permo-Triassic metasediments crop out also within the Leventina-Lucomagno Nappe, likely as pinched synclines (e.g., Molare Syncline; see Fig. 7) or as intranappe slices.