Gruppo d'Antabia

Representation and status

Color CMYK

(22%,11%,0%,12%)

Color RGB

R: 175 G: 200 B: 225

Rank

lithostratigraphic Group

Validity

Unit is in Use

Status

informal term

Nomenclature

Deutsch

Antabia-Gruppe

Français

Groupe d'Antabia

Italiano

Gruppo d'Antabia

English

Antabia Group

Origin of the Name

Val (d')Antabia (TI)

Historical Variants

Massiger, gelblicher, bläulicher oder weisser Kalkmaror = basale Glieder der Bündnerschieferserie im Val Antabia (Günthert 1958), Antabia group (Matasci et al. 2011 p.261)

Hierarchy and sequence

Subordinate units

• Formazione dei Vanis
• Marmo di Sevinèra
• Arenaria di Sevinèra
• Conglomerato del Ri d'Antabia

Units at roof

• Calcescisti del Teggiolo

Age

Age at top

• Berriasian

Age at base

• Early Jurassic

Geography

Geographical extent

Lepontin

Type area

Val d'Antabia (TI)

Palaenography and tectonic

Tectonic unit (resp. main category)

• Sambuco

Kind of protolith

• sedimentary

References

Definition

Matasci Battista, Epard Jean-Luc, Masson Henri (2011) : The Teggiolo zone: a key to the Helvetic–Penninic connection (stratigraphy and tectonics in the Val Bavona, Ticino, Central Alps). Swiss J. Geosci. 104, 257–283

p.263: We have defined in the Teggiolo zone four distinct stratigraphic units above the Triassic dolomite. They are from bottom upwards: (1) the Ri d’Antabia conglomerate (sporadic); (2) the Sevinèra sandstone; (3) the Sevinèra marble; and (4) the Vanis banded marble/calcschist. They are all separated by sharp limits, are easily mappable and have a regional extent (with the exception of the conglomerate, which is discontinuous but nevertheless forms a mappable unit). Consequently they are conveniently treated as lithostratigraphic formations. It is useful to define this whole set of formations as a lithostratigraphic group that we call the Antabia group, because the most complete cross-section is exposed in the Val Antabia where we also observe its truncation by the base of the next sedimentary cycle. The basal contact of this group on the Paleozoic gneiss or the Triassic dolomite is definitely stratigraphic and erosive, as described above, and the immediately underlying rocks never show any hint of unusual tectonization. In the classical literature the Antabia group is simply called ‘‘marble’’ and is ascribed to the Triassic. In the light of modern Alpine stratigraphy, this age can be absolutely excluded for at least three reasons: (1) At several places the Ri d’Antabia conglomerate erodes and reworks the Triassic dolomite. (2) More generally, the conglomerate and the Sevinèra sandstone have no place in the Triassic paleogeography of the Central and Western Alps (see Mégard- Galli and Baud 1977); and ascribing these rocks to the Triassic would imply a complete change of the paleogeographic and geodynamic reconstructions. (3) The main reason for the Triassic attribution seems to be a tentative correlation of the marbles with the thick limestone layers of the Triassic Briançonnais province. However, the Briançonnais Triassic limestones have very specific lithological characteristics (Baud and Mégard-Galli 1975; Baud 1987) that do not correspond at all to the Sevinèra marbles.