Nair-Porphyroid

Representation and status

Color CMYK

(0%,51%,64%,24%)

Color RGB

R: 195 G: 95 B: 70

Rank

lithostratigraphic Formation

Validity

Unit is in Use

Status

informal term

Status discussion

Nomenclature

Deutsch

Nair-Porphyroid

Français

Porphyroïde du Piz Nair

Italiano

Porfiroido del Piz Nair

English

Nair Porphyroid

Origin of the Name

Piz Nair = Piz Neir (GR) im Juliergebiet

Historical Variants

Nairporphyr (Cornelius 1912), Nairporphyroid (Cornelius 1932, Cornelius 1935), Quarzporphyr vom Typus Piz Prascheng [Piz Barscheinz] = Nairporphyr (Staub 1946), Nair-Porphyr = Nair-Porphyroid (Rutsch et al. 1966), Volcanics of the LAA = Nair Porphyroid (Furrer et al. 1985), Neir-Porphyroid (Manatschal & Nievergelt 1997), Neirporphyr / Neirvulkanite

Description

Thickness

z.T. mehrere hundert Meter

Hierarchy and sequence

Superordinate unit

• Vulkanite des Karbons

Subordinate units

• Lavatèra-Brekzie
• «Pyritquarzit»

Age

Age at top

• Carboniferous

Age at base

• Carboniferous

Geography

Geographical extent

Carungas, Grevasalvas, Bardella, Nair (Err-Decke).

Type area

Julierpassgebiet (GR) (Err-Decke)

Palaenography and tectonic

Tectonic unit (resp. main category)

• Err-DK
• Bernina-DK

Conditions of formation

Bimodal kalk-alkalischer Vulkanismus (Rhyodazit und Quarz-Andesite).

Metamorphism

monocyclic

Metamorphic facies

• greenschist facies (epizone)

References

Definition

Cornelius H. P. (1912) : Petrographische Untersuchungen in den Bergen zwischen Septimer- und Julierpass. N. Jb. Min., etc. 35, 374-

Definition

Furrer Heinz (Ed.) (1985) : Field workshop on Triassic and Jurassic sediments in the Eastern Alps of Switzerland. Mitt. geol. Inst. ETH und Univ. Zürich (N.F.) 248, 81 S.

p.16: In the LAA similar volcanics and volcanoclastics occur [as in the Ruina Fm.]. The Nair Porphyroid of the Err nappe (Cornelius 1812, 1935) in the Julier pass area consists of a series of metavolcanics (lower greenschist facies) with rhyolitic to dacitic chemistry. (Presence of Quarz-Andesite indicates a bimodal volcanism of the Calc-alcaline group). In the Bernina pass area massive Alkalifeldspar-rhyolites are found. These posthercynian volcanics may be considered as equivalents of the Ruina Fm. in the CAA.