Banc du Col de la Plaine Morte

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Representation and status

Color CMYK
(0%,37%,37%,4%)
Color RGB
R: 245 G: 155 B: 155
Rank
lithostratigraphic Bed
Validity
Unit is in Use
Status
local name (informal)
Scs Note

Nicht zu verwenden: unnötig da sehr lokal ; Ortsname schon für eine andere lithostratigraphische Einheit verwendet (Wildflysch de la Plaine Morte).

Scs Date
18.10.2007
Status discussion

Nomenclature

Deutsch
Col-de-la-Plaine-Morte-Bank
Français
Banc du Col de la Plaine Morte
Italiano
Strato del Col de la Plaine Morte
English
Col de la Plaine Morte Bed
Origin of the Name

Col de la Plaine Morte (VS)

Historical Variants

Plaine Morte Bed (Föllmi et al. 2006 et 2007, Föllmi & Gainon 2008, Föllmi 2009)

Description

Thickness
max. 20 cm

Components

Fossil Content
  • ammonites

Deshayesites, Aconeceras

Hierarchy and sequence

Superordinate unit

Age

Age at top
  • Early Aptian
Note about top

Untere Abschnitt der furcata-Zone

Age at base
  • Early Aptian
Note about base

Obere Abschnitt der deshayesi-Zone

Geography

Geographical extent
Nur lokal im Rawilgebiet.
Type area
Rawilgebiet (VS/BE)
Type locality
  • Col de la Plaine Morte - Rohrbachstein (VS/BE)
    Site particularities
    • Obergrenze
    • Untergrenze
    • typische Fazies
    Coordinates
    • (2601250 / 1136320)
    Note
    • <p>Typlokalität der Rohrbachstein-Bank und der Col-de-la-Plaine-Morte-Bank (Föllmi et al. 2007)</p>
Type profile
  • Col de la Plaine Morte - Rohrbachstein (VS/BE)
    Site particularities
    • Obergrenze
    • Untergrenze
    • typische Fazies
    Coordinates
    • (2601250 / 1136320)
    Note
    • <p>Typlokalität der Rohrbachstein-Bank und der Col-de-la-Plaine-Morte-Bank (Föllmi et al. 2007)</p>

Palaenography and tectonic

Tectonic unit (resp. main category)
Kind of protolith
  • sedimentary

References

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.12: In the Rawil area, the lower part of the Grünten Member is covered by a thin, nodular glauconite- and phosphate-containing layer, in which sparse phosphate particles occur. The limestone nodules are peripherically phosphatized. For this bed we propose the name Plaine Morte Bed (Fig. 2, Fig. 8; Gainon 2001), with as type locality the same outcrop as described above for the Rohrbachstein Bed. The Plaine Morte Bed signals again an episode of platform drowning.
Definition
Föllmi Karl B. (2009) : Neubenennungen lithostratigraphischer Einheiten in der helvetischen Kreide - Comment on the article by the Schweizerisches Komitee für Stratigraphie (SJG, Vol 102/2): What is in a stratigraphical name? Swiss J. Geosci. 102 (2009) 515–518

The Plaine-Morte Bed

In the area of the Col de la Plaine Morte, the Plaine-Morte Bed embodies an approximately 20-cm thick nodular phosphatic layer within the Grünten Member, which is well distinguishable in the field. The Plaine-Morte Bed includes large clasts composed of crinoidal limestone of the lower Grünten Beds, which are peripherically phosphatized and small phosphatic nodules and particles. Sparse ammonites indicate the deshayesi and furcata ammonite zones (Föllmi & Gainon 2008). In this region, the Plaine-Morte Bed merges laterally with the higher Luitere

Bed, and the intervening upper Grünten Beds disappear.

The importance of this bed is that it helps us to explain the older ages shown in distal occurrences of the Luitere Bed in Allgäu and Vorarlberg, where ammonites are present from the deshayesi and furcata ammonite zones (besides younger ammonites indicating the early Late Aptian). These older ages can be explained by the Luitere Bed being merged with the Plaine-Morte Bed, in analogy of what is observed in the area of the Col de la Plaine Morte. This merging pattern is well comparable to the merging of different phosphorite beds into one singe bed

higher up in the Garschella Formation.

To this comes that with the Plaine-Morte Bed, the imprint of oceanic anoxic event 1a (the so-called “Selli event”) has been discovered on the northern Tethyan margin. (...)
Important Publications
Schweizerisches Komitee für Stratigraphie (2009) : Statement to comment by K. Föllmi on „Neubenennungen lithostratigraphischer Einheiten in der helvetischen Kreide“ Swiss J. Geosci. 102 (2009) 519
Föllmi Karl B., Gainon François (2008) : Demise of the northern Tethyan Urgonian carbonate platform and subsequent transition towards pelagic conditions: the sedimentary record of the Col de la Plaine Morte area, central Switzerland Sedimentary Geology 205, 142–159
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
Schweizerisches Komitee für Stratigraphie (2009) : Neubenennungen lithostratigraphischer Einheiten in der Helvetischen Kreide Swiss J. Geosci. 102/2, 363-364
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