Falda di Suretta

Back to Suretta nappe

Representation and status

Index
Su, Sur
Color CMYK
N/A
Color RGB
R: 241 G: 239 B: 237
Rank
nappe
Validity
Unit is in Use
Status
valid

Nomenclature

Deutsch
Suretta-Decke
Français
Nappe de Suretta
Italiano
Falda di Suretta
English
Suretta Nappe
Origin of the Name

Surettahorn (GR)

Historical Variants

Suretta-Decke (Cornelius 1932), Surettadecke (Wilhelm 1933, Staub 1934, Spillmann 1993), Suretta-Decke (Staub 1946, Schmutz 1976), Falda Suretta (Godenzi 1963), Suretta nappe (Milnes & Schmutz 1978), falda Suretta (Sciesa 1991), nappe de Suretta (Mayerat Demarne 1994), Suretta Nappe (TK500 / Gouffon et al. 2024)

Nomenclatorial Remarks

cf. Marquer et al. 1994, Marquer & Peucat 1994

Description

Description

Mittelpenninische Decke der Ostalpen, bestehend aus einem kristallinem Grundgebirge (Ortho- und Paragneise) mit seiner autochthonen Sedimentbedeckung (klastische und karbonatische Plattformsedimente).

"puissant ensemble de cristallin anté-carbonifère, avec des restes d'une couverture mésozoïque" (Trümpy 1976)

Hierarchy and sequence

Subordinate units
Upper boundary

Avers-Decke: "Im Avers und im Valmalenco folgen darüber Kalkschiefer, welche ohne genaue lithologische und tektonische Trennung übergehen in inhomogene, sandig-tonig-kalkige Metasedimente, welche meta-ophiolithisches Material (Metaggabros, Prasinite, Serpentinite) und zugehörige südpenninische Sedimente (Radiolarit, Aptychenkalk, Palombini) enthalten (Montrasio 1984, Liniger & Nivergelt 1990, Liniger 1992)." (Spillmann 1993 S.14)

Geography

Geographical extent
Andeer, Surettahorn, Piz Timun, Valle di Lei, Piz Stella, Piz Duan, Val Bregaglia, sowie Val Malenco (Lanzada-Fenster).

Palaenography and tectonic

Paleogeography
Briançonnais Terrane :

microcontinent briançonnais

Tectonic unit (resp. main category)
Kind of protolith
  • tectonic

References

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

p.75: The Suretta Nappe also has a Paleozoic basement of para- and orthogneisses intruded by the Permian Rofna Porphyry Complex, which consists of granitoids and effusive-type magmatites (Marquer et al. 1998). Its Permian – Mesozoic cover, again in Briançonnais facies, is largely of Triassic age. Locally the Triassic is overlain by Jurassic breccias. This cover crops out as thin layers; in one instance it follows a Suretta-internal thrust fault, in other instances they are infolded into narrow synclines that were subsequently backfolded in the upper limb of the north facing Niemet-Beverin Backfold, whose axial trace runs across the Suretta Nappe (Scheiber et al. 2012).
Two small windows (Lanzada Windows), dominated by sedimentary rocks typical for the Suretta Nappe, are located in the Val Malenco and surrounded by the Malenco-Forno-Lizun Nappe (Montrasio 1984, Montrasio et al. 2005). These windows also expose some small occurrences of metagabbro and ultramafics that are correlated with the Avers Nappe.

  • Finestre di Lanzada

    Name Origin

    Lanzada (Valmalenco, Italia)

    Rank
    window
    Status
    informal term
    In short

    The Lanzada Fensters, in the Val Malenco, are two small tectonic windows dominated by sedimentary rocks typical for the Suretta Nappe and surrounded by the Malenco-Forno-Lizun Nappe. These windows also expose some small occurrences of metagabbro and ultramafics that are correlated with the Avers Nappe.

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