Blattengrat-Sandstein

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Representation and status

Color CMYK
(0%,4%,51%,4%)
Color RGB
R: 245 G: 235 B: 120
Rank
lithostratigraphic unit
Validity
Unit is in Use
Status
valid formal name
Status discussion

Nomenclature

Deutsch
Blattengrat-Sandstein
Français
Grès du Blattengrat
Italiano
Arenaria del Blattengrat
English
Blattengrat Sandstone
Origin of the Name

Blattengrat (GL), nord-östlich von Elm (Sernftal)

Historical Variants

Blattengratsandstein = priaboner Sandsteinflysch (Bisig 1957), Blattengratsandstein (Wegmann 1961), Südhelvetischer Flysch der Ostschweiz (Typus Blattengrat-Sandstein) (Bayer 1982), Blattengratflysch, Blattengrat-Serie, Blattengrat Sandstone (Menkveld et al. 2016), Blattengrat-Sandstein (Löpfe et al. 2018)

Nomenclatorial Remarks

siehe auch Herb 1962

Description

Thickness
Max. ein paar Zehnte Meter (Menkveld-Gfeller et al. 2016).

Hierarchy and sequence

Units at floor
Upper boundary

Tektonisches Kontakt.

Lower boundary

Stad-Fm. bzw. Muot-da-Rubi-Fm.

Age

Age at top
  • Priabonian
Age at base
  • Priabonian
Dating Method

Benthonische Grossforaminiferen: Heterostegina helvetica (Bisig 1957) ; Mittel- bis Späteozän (Bayer 1982).

Geography

Geographical extent
Ostschweiz (Sernftal, Glarus, St.Galler Oberland).
Type area
Südliches Glarnerland.
Type locality
  • Blattengratt (GL), NE Elm
    Site particularities
    • typische Fazies
    Site accessibility
    • Grat
    Coordinates
    • (2734540 / 1201260)
    Note
    • Bisig 1957
Type profile

Palaenography and tectonic

  • South-Helvetic Flysch
Paleogeography
South Helvetic Domain
Tectonic unit (resp. main category)
Kind of protolith
  • sedimentary
Metamorphism
monocyclic-monophase

References

Definition
Bisig Walter Karl (1957) : Blattengratflysch und Sardonaflysch im Sernftal nördlich der Linie Richetlipass - Elm - Ramintal - Grosse Scheibe Mitt. geol. Inst. ETHZ, Serie C, Nr.74

S.240: Die Globigerinenschichten gehen über in “einen Sandsteinflyschkomplex". Zuerst treten in den obersten Partien der Globigerinenkalke Feinsandschlieren auf, darauf setzt eine Wechsellagerung von Fleckenkalken mit feinkörnigen Glimmersandsteineinlagen ein, die schliesslich rasch übergeht in eine Floge von überwiegend Glimmersandkalkbänken.

Definition
Menkveld-Gfeller Ursula, Kempf Oliver, Funk Hanspeter (2016) : Lithostratigraphic units of the Helvetic Palaeogene: review, new definition, new classification. Swiss J. Geosc. 109/2, 171-199

p.192: Bisig (1957) first described the Blattengrat Sandstone (Formation; Blattengrat-Sandstein) from its type locality at Blattengrat, northeast of Elm, Sernf valley (at P. 2248: 2734.540/1201.260). For further descriptions see Arn. Heim (1911) and Oberholzer (1933; ‘‘Blattengratschichten’’ pro parte); Leupold (1942); Lihou (1995).

The Blattengrat Sandstone, as true flysch deposit, is part of the so called ‘‘wrapped’’ flysch (‘‘eingewickelter Flysch’’, Arn. Heim 1911) representing the youngest and uppermost sediment succession of the Blattengrat nappe. There is a thin, basal unit of transitional sediments—sandstone beds in marlstone—that can be related to the Muot-da-Rubi Formation. However, since this unit is not mapable at 1:25’000 scale, we consider it as part of the above following Blattengrat Sandstone.

Lithology: The Stad Formation, comprising here a patchy marlstone (‘‘Fleckenmergel’’), terminates with the first occurrence of sand lenses in the marlstone (i.e., representing the Muot-da-Rubi Formation). It is succeeded by mica-sandstone beds, the proper Blattengrat Sandstone, which alternates with thin beds of patchy, more or less siliceous limestone (‘‘Fleckenkalk’’). The Blattengrat Sandstone consists of coarse-grained quartz sand and mica; a Fe-bearing variety of the latter appears reddish on a weathered surface. Black slate fragments and siliceous and calcareous pebbles may additionally be present, as well as fragments of Cretaceous and Palaeogene reworked foraminifera. Priabonian foraminifera (Heterostegina helvetica), known from the Subalpine Flysch zone, can also occur. The thickness is a few tens of meters at most. Overlying strata: tectonic boundary; underlying strata: Stad Formation (‘‘Fleckenmergel’’), Muot-da-Rubi Formation. Biostratigraphy: Priabonian, foraminfera. Current geographical extent: Eastern Switzerland: Sernf valley. Tectonic units: Eastern Switzerland: Blattengrat nappe, Bad-Ragaz nappe.

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