Nappe des Cimes Blanches
Back to Cimes Blanches NappeRepresentation and status
- Index
- CB
- Color CMYK
- N/A
- Color RGB
- R: 241 G: 239 B: 237
- Rank
- nappe
- Validity
- Unit is in Use
- Status
- valid
- Status discussion
Nomenclature
- Deutsch
- Cimes-Blanches-Decke
- Français
- Nappe des Cimes Blanches
- Italiano
- Falda delle Cime Bianche
- English
- Cimes Blanches Nappe
- Origin of the Name
- Historical Variants
-
Faisceau vermiculaire p.p. (Argand 1916), complesso triassico basale (Dal Piaz 1965), série des Cimes Blanches (Vannay & Allemann 1990), nappe des Cimes Blanches (Escher et al. 1993), nappe de décollement des Cimes Blanches (Sartori et al. 2006), unità Pancherot-Cime Bianche-Bettaforca (Dal Piaz et al. 1992a), Unità Pancherot - Cime Bianche = Pancherot-Cime Bianche unit (Dal Piaz et al. 2015), Cimes Blanches nappe = Cimes Blanches unit (Steck et al. 2015), Cimes Blanches Nappe (TK500, Gouffon et al. 2024)
Description
- Description
-
Mince bande de gneiss albitiques, de quartzites, de dolomies et de brèches intercalée dans la nappe du Tsaté, à proximité du contact avec la nappe de Zermatt-Saas. La série stratigraphique rappelle celle de la nappe de la Brèche (Préalpes) [ou le Sudalpin], mais est affectée par une tectonique d'inversion complexe, héritée de blocs basculés lors du rifting téthysien au Jurassique.
Cf. Kramar 1997, Sartori et al. 2005, Dal Piaz et al. 2015: brownish calcschists (Cretaceous?), slope breccias with dolomitic fragments (Jurassic?), dolostones and marbles (Middle-Late Triassic), basal siliciclastic successions (Permian-Eotriassic?)
Dal Piaz et al. 1992a p.50: Nell'alta Val d'Ayas e in Valtournenche vi si associata una sottile unità basale, priva di ofioliti, costituita da metasedimenti permo-mesozoico fortemente trasposti, scollati dal margine continentale adriatico (unità Pancherot-Cime Bianche-Bettaforca, correlabile all'unità del Frilihorn nel Vallese; Marthaler 1984, Escher et al. 1987).
- Thickness
- 50-150 m (Vannay & Allemann 1990) ; série perturbée par des répétitions tectoniques (plis isoclinaux, écaillage).
Age
- Age at top
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- Mesozoic
- Age at base
-
- Permian
- Dating Method
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Par analogie de faciès avec des séries similaires, notamment la série du Barrhorn (Vannay & Allemann 1990).
Geography
- Geographical extent
- Unité restreinte à la région Zermatt – Valtournenche (Cimes Blanches, Mont Pancherot sur le versant italien). Une extension plus grande avait été considérée par le passé.
- Type area
- Haut-Valtournanche (Italia)
Palaenography and tectonic
- Paleogeography
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Prepiemont Domain
,
Briançonnais Terrane
:
microcontinent briançonnais
- Tectonic unit (resp. main category)
- Conditions of formation
-
faciès de plateforme et de pied de pente (Vannay & Allemann 1990)
References
- Definition
-
(2024) :
Tectonic Map of Switzerland 1:500000, Explanatory notes. Federal Office of Topography swisstopo, Wabern
p.69: In the Val d’Anniviers, Zermatt Valley and Valtournanche, a few thin tectonic units are located at the contact between the Middle and Upper Penninic (Gornergrat Nappe) or are intercalated within the Tsaté Nappe (Frilihorn and Cimes Blanches 1) nappes). They are all composed of a series of Briançonnais-type Permian – Triassic sediments overlain by Jurassic breccias and limestone and calcschists probably of Cretaceous age. As their lithology is quite similar to that of the Mont Fort Nappe, their paleogeographic origin can also be located in the pre-Piemonte realm (transition zone between Briançonnais Terrane and Piemonte-Liguria Ocean); however, an Adriatic origin has also been proposed (“Austroalpine”, Dal Piaz 1999 and ref. therein). An eastward extension of the Mont Fort Nappe was often considered for these three narrow nappes (e. g., Argand 1909, Escher 1988, Pantet 2022).