Graspass-Member

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Representation and status

Color CMYK
siehe Zementstein-Fm.
Color RGB
R: 160 G: 195 B: 190
Rank
lithostratigraphic Member (Subformation)
Validity
Unit is in Use
Status
informal term

Nomenclature

Deutsch
Graspass-Member
Français
Membre du Graspass
Italiano
Membro del Graspass
English
Graspass Member
Origin of the Name

Graspass (BE) in den Engelhörnern (zwischen Tannenspitze und Engelburg = Sattelspitze)

Historical Variants

Troskalkbreccie (Keller 1912), Graspassschichten (Arbenz & Müller 1920, Rohr 1926, Scabell 1926 S.40), Grenzschichten (Gerber 1930: Axen-Decke, Maync 1938), Brèche du Steinmann (Collet 1936: nappe de Morcles), Obertithonbreccie (Guenzler 1938: Wildhorn-Decke der Faulhorn-Gruppe), Graspass-Schichten (Müller 1938, Rutsch et al. 1966), Graspass Member (Föllmi et al. 2007)

Description

Description

Kalkige oder dolomitische Brekzie und bläulichgrau anwitternde Mergel an der Basis der Zementstein-Formation.

Thickness
Mehrere Dezimeter bis 5 - 12 m (Arbenz & Müller 1920).

Components

Fossil Content
  • gastropods
  • algae
  • foraminifera
  • charophytes

Mohr 1992a

Hierarchy and sequence

Superordinate unit
Units at roof
Units at floor
Upper boundary

Öhrli-Kalk

Geography

Type area
Berner Oberland (BE)
Point of interest

Palaenography and tectonic

  • Cretaceous of the Helvetics
Paleogeography
North Tethyan Shelf :
marge continentale européenne
Tectonic unit (resp. main category)
Kind of protolith
  • sedimentary
Conditions of formation

Impoverished Platform facies. highstand system tract (Föllmi et al. 2007)

References

Definition
Arbenz P., Müller F. (1920) : Über die Tektonik der Engelhörner bei Meiringen und den Bau der parautochthonen Zone zwischen Grindelwald und Engelberg. Eclogae geol. Helv. 16/1, 111-116

S.114: »Graspassschichten«: wenig mächtige, aber sehr konstant auftretende kalkige oder dolomitische Breccien (ähnlich Breccien im obersten Malm des Glarnerlandes), ferner bläulichgrau anwitternde Mergel, 5—12 m. Wir glauben in diesen Schichten den obersten Malm und die Zementsteinschichten zu sehen und somit die Grenze gegen die Kreide. (Gletscherhubel, Graspass, Ochsental, Burgalpli, Reichenbachstrasse).

Definition
Föllmi Karl B., Bodin Stephane, Godet Alexis, Linder Pascal, van de Schootbrugge B. (2007) : Unlocking paleo- environmental information from Early Cretaceous shelf sediments in the Helvetic Alps: stratigraphy is the key! Swiss J. Geosci. 100, 349-369

p.5: The sequence boundary between the Tros Member and the overlying sequence (Zementstein Formation; Fig. 2; Diegel 1973; Mohr 1992a) is marked in the platform area itself by brecciated layers, dolomite and brackish to lacustrine facies, and signs of erosion and sediment reworking are abundant. The overlying platform sediments of the Zementstein Formation are merely several dm thick and document an impoverished platform facies (Graspass Member; Arbenz & Müller 1920), which is dominated by the deposition of marine clay-rich sediments containing peloids, miliolids, gastropods and calcarous algae, and brackish-lacustrine sediments rich in charophytes (Mohr 1992a). This succession is interpreted as the highstand systems tract of a second platform sequence, which extends upwards into the Middle Berriasian.

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