intrusione della Bregaglia

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Représentation et statut

Index
Ber
Couleur CMYK
(0%,100%,80%,2%)
Couleur RGB
R: 250 G: 0 B: 50
Rang
Groupe lithostratigraphique
Usage
Ce terme est en usage.
Status
terme informel
Discussion du statut

Nomenclature

Deutsch
Bregaglia-Intrusion
Français
intrusion de la Bregaglia
Italiano
intrusione della Bregaglia
English
Bregaglia intrusion
Origine du nom

SO Val Bregaglia

Variantes historiques

Granite der Valle della Mera = Granite der Bassa Valle della Mera (Wenk 1956), batolite bregagliotta = Massiccio Bregagliotto (Godenzi 1963), Bergeller Intrusion = tertiäre synorogene granitoide Intrusiva des Bergell (Bucher-Nurminen 1970), Zone Giubasco-Jorio-Sorico-Monte Bassetta-Val Masino-Monte Sissone = Zone Jorio-Sissone = Serizzo-Zug (Wenk 1982), Bregaglia-Iorio Intrusive (Trommsdorf & Nivergelt 1986), plutone di Val Màsino-Bregaglia-Iorio (Sciesa 1991), plutoniti di Bregaglia (Dal Piaz et al. 1992a), intrusion de la Bregaglia (Mayerat Demarne 1994), Masino-Bregaglia igneous body (Hansmann 1996), Plutone Val Masino-Bregaglia (Spalla et al. 1998), Complesso di Bregaglia (Wenk 2012)

Âge

Âge au sommet
  • Oligocène
Âge à la base
  • Oligocène
Méthode de datation

32-30 Ma

Géographie

Extension géographique
Massiccio intrusivo compresso fra le Valli Bregaglia, Masino e Malenco.
Région-type
Val Bregaglia (GR)

Paléogéographie et tectonique

Termes génériques
Type de protolithe
  • plutonique
Conditions de formation

Hansmann 1996 S.422: Field evidence defines the following magmatic sequence in the MB area:

(i) Andesitic-basaltic dikes that crosscut the Alpine fohation in the neighbouring units (Nievergelt and Dietrich, 1977) show a contact metamorphic overprint in the MB aureole (Gautschi and Montrasio, 1978).These were interpreted as precursors of the main intrusions on geochemical grounds (Diethelm, 1989; von Blanckenburg et al., 1992).

(ii) Gabbros and hornblendites occur as variously-sized inclusions only in the tonahte and are interpreted as early magmatic differentiates (Diethelm, 1985,1989).

(iii) The two main intrusions, the tonalite ("Serizzo") and the granodiorite ("Serizzo Ghiandone" in the older Italian hteräture). These are in-contact along a complex transition zone (Moticska, 1970; Reusser. 1987) but age relationships of the two are ambiguous in the western part of the main igneous body. The tonalite is considered to be older (e.g. Cornelius, 1928; Bucher-Nurminen, 1977; Berger and Giere, 1995). Field evidence in support of this hypothesis is given by a small granodioritic stock intruding the tonahte in the Val Sissone (Montrasio and Trommsdorff, 1983; Berger and Giere, 1995).

(iv) Lamprophyric dikes of calc-alkaline and shoshonitic compositions are present in the granodiorite with variable degrees of disintegration from undisturbed dikes through disrupted dikes and swarms of inclusions to isolated inclusions. These dikes intruded the granodioritic magma prior to its complete sohdification (Diethelm, 1989).

(v) The youngest major intrusion in the area is represented by a garnet-bearing two-mica-leucogranite, the Novate Granite. Pegmatites, leucocratic inicro-granjtes and aplites are widespread in the whole MB region. Some of these dikes radiate from the Novate intrusion. Among the several generations of leucocratic dikes (e.g. Moticska, 1970), Reusser (1987) distinguished pre- and post granodioritic types, therefore only some of the dikes can actually be associated with the Novate intrusion.

  • Aplite di Zocca

    Name Origin

    Pizzo di Zocca (GR)/(Italia)

    Rang
    unité lithostratigraphique
    Statut
    terme local (informel)
    En bref

    Filoni aplitici e pegmatitici.

  • Microgranito del Monte Rosso

    Rang
    unité lithostratigraphique
    Statut
    terme local (informel)
  • Granodiorite dell'Alpe Cameraccio

    Name Origin

    Alpe Cameraccio (Italia)

    Rang
    Formation lithostratigraphique
    Statut
    terme local (informel)
    En bref
    Granodiorite massicco a grana fine, senza megacristalli.
  • Minestronite

    Rang
    faciès pétrographique
    Statut
    terme incorrect (mais utilisé de manière informelle)
    En bref
    Brecce di gabbri, di serzzo e di rocce incassanti, cementate da ghiandone.
  • Granodiorite della Bregaglia (ghiandone)

    Rang
    Formation lithostratigraphique
    Statut
    terme informel
    Nomenclatorial Remarks
    Ghiandone auct.
    En bref
    Granodioritischer Kern der Bergell-Intrusion.
    Age
    Oligocène précoce
    • Granodiorite della Val Màsino

      Name Origin

      Val Masino (Italia)

      Statut
      terme formel valide
      Nomenclatorial Remarks
      ghiandone auct., Bergellergranit, Disgraziagranit [sic]
      En bref
      Granodiorite con porfiroblasti di K-feldspato, talora orientati, da la parte centrale ed orientale del plutone della Val-Màsino-Bregaglia-Iorio.
      Age
      Oligocène précoce
    • Melirolo-Augengneis

      Name Origin

      Melirolo (TI), Val Morobbia

      Statut
      terme informel
      En bref
      Granodiorite ad orneblenda, con "occhi" di plagioclasio. Südliche Randfazies des Iorio-Tonalites.
  • Tonalite della Bregaglia (serizzo)

    Rang
    Formation lithostratigraphique
    Statut
    terme informel
    Nomenclatorial Remarks
    serizzo auct., Hornblendegneiss (Théobald 1866 S.254), Syenit (Théobald 1866 S.256), gneiss anfibolico (porphiroide) (Melzi 1893 S.110)
    En bref
    Tonalitische (quarzdioritische) Hülle der Bergell-Intrusion, die von der Bergell-Granodiorit intrudiert und vergneist wurde.
    Age
    Oligocène précoce
    • Quarzdiorite del Monte Bassetta

      Name Origin

      Monte Bassetta (Italia)

      Statut
      terme formel valide
      Nomenclatorial Remarks
      serizzo auct., Bergell-Tonalit, Masino-Tonalit
      En bref
      Diorite quarzosa epidotica, orientata, con passagi a tonaliti o gabbri al bordo meridionale e sud-orientale del plutone di Val Màsino-Bregaglia-Iorio.
      Age
      Oligocène précoce
    • Tonalite di Sòrico

      Name Origin

      Sòrico (Italia)

      Statut
      terme local (informel)
      En bref
      Tonaliti e dioriti epidotiche, simili al serizzo, ma più laminate, con frequenti inclusi basici e di rocce incassanti.
    • Tonalite di San Iorio

      Name Origin

      Passo di San Iorio (TI)

      Statut
      terme local (informel)
      Nomenclatorial Remarks
      Horneblendegneiss auct.
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