Pesciora-Gruppe (Postvariszische Intrusiva)

Representation and status

Color CMYK

(0%,40%,57%,8%)

Color RGB

R: 235 G: 140 B: 100

Rank

lithostratigraphic Group

Validity

Unit is in Use

Status

informal term

Nomenclature

Deutsch

Pesciora-Gruppe (Postvariszische Intrusiva)

Français

Groupe de Pesciora

Italiano

Gruppo di Pesciora

English

Pesciora Group

Origin of the Name

Pizzo Pesciora (VS), Obergoms

Historical Variants

Jüngere Granite (Spillmann et al. 2011), Pesciora Group (Berger et al. 2017)

Nomenclatorial Remarks

cf. Passo di Pesciora

Hierarchy and sequence

Subordinate units

• Winterhorn-Granit
• Cacciola-Granit
• Rotondo-Granit
• Prosa-Granit
• Val-Tremola-Granit
• Sädelhorn-Diorit

Age

Age at top

• Sakmarian

Age at base

• Sakmarian

Palaenography and tectonic

• Variscan plutonic rocks of the Helvetic

Paleogeography

European Continent

Tectonic unit (resp. main category)

• Gotthard

Kind of protolith

• plutonic

References

Definition

Berger Alfons, Mercolli Ivan, Herwegh Marco, Gnos Edwin (2017) : Geological Map of the Aar Massif, Tavetsch and Gotthard Nappes. Geological Special Map 1:100'000, Explanatory Notes 129

p.73: At map scale, the Rotondo Granite, representing the largest granitic body of this group with an exposed surface of ~25 km2, has a pronounced, rounded shape, with sharp discordant contacts to the surrounding gneisses of the polycyclic metamorphic basement. Its microstructure is massive and essentially undeformed; locally garnet occurs. Due to this, it was suggested that the intrusion could be of Alpine age (HAFNER 1958). The other small granite bodies intrude along the boundaries of the two larger and slightly older Fibbia Granite and Gamsboden Granite. The close spatial link between the granites of the Pesciora Group and those of the Val Lavaz Group underline an almost continuous intrusive activity as suggested by the age relationship.
SERGEEV et al.(1995) obtained an U/Pb age on zircon of 294± 1,1 Ma for the Rotondo Granite and the Tremola Granite (Fig. 4). SERGEEV & STEIGER (1995) suggested an age interval of 5,5 Ma for the intrusion of the Rotondo, Winterhorn, Cacciola, Prosa and Tremola Granites with an average age of 294,5+3,5/–2 Ma. OBERLI et al.(1981) obtained an age of 292±11 Ma for the Cacciola Granite, and BOSSART et al.(1986) an age of 293+4/–5 Ma for the Sädelhorn Diorite, both in agreement with the ages of the granitic members of the group. This time interval corresponds well with Early Permian (Sakmarian, 295– 290 Ma).