Rohrbachstein-Bank
Retour à Nappe de MorclesReprésentation et statut
- Couleur CMYK
- (0%,37%,37%,4%)
- Couleur RGB
- R: 245 G: 155 B: 155
- Rang
- Banc lithostratigraphique
- Usage
- Ce terme est en usage.
- Status
- terme informel
- Scs Note
-
Bewilligt, aber nur informell zu verwenden.
- Scs Date
- 18.10.2007
- Discussion du statut
Nomenclature
- Deutsch
- Rohrbachstein-Bank
- Français
- Banc du Rohrbachstein
- Italiano
- Strato del Rohrbachstein
- English
- Rohrbachstein Bed
- Origine du nom
-
Westflank des Rohrbachsteins (VS)/(BE), Rawilgebiet
- Variantes historiques
-
Rohrbachstein Bed (Föllmi et al. 2006, Föllmi et al. 2007, Föllmi & Gainon 2008, Föllmi 2009)
Description
- Description
-
Grobkörniger Kalkarenit von Material heterozoer Organismen. Glaukonitführend, untergeordnet detr. Quarz und Phosphorit-Partikel. Oft assoziiert mit einem bioturbierten firm- oder einem lokal phosphatisierten, durchbohrten hardground im Dach der Schrattenkalk-Formation.
Composants
- glauconite
Hiérarchie et succession
- Unité hiérarchiquement supérieure
- Unités sus-jacentes
- Unités sous-jacentes
- Limite supérieure
-
Überlagert von den oft eher mergeligeren und etwas feinkörnigeren Sedimenten des Grünten-Members.
- Limite inférieure
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Hebt sich gut ab vom unterliegenden Schrattenkalk durch eine unterschiedliche Lithologie und durch das Vorhandensein einer deutlich ausgeprägten Grenzfläche.
- Discussion stratigraphique
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Lateral kann diese Schicht nur durch eine Omissionsfläche an der Obergrenze des Schrattenkalks ersetzt werden, die lokal phosphatisiert ist.
Âge
- Âge au sommet
-
- Aptien précoce
- Âge à la base
-
- Aptien précoce
- Méthode de datation
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Sequenzstratigraphische Korrelation mit Vercors
Géographie
- Extension géographique
- Mehrere Gebiete mit lokaler Verbreitung: Berner Oberland (Rawilgebiet), Zentralschweiz (Fronalpstock, Bauen-Brisen-Gebiet), Allgäu (Grünten).
- Région-type
- Rawilgebiet (VS/BE)
- Localité-type
-
-
Col de la Plaine Morte - Rohrbachstein (VS/BE)
Particularités du site- Obergrenze
- Untergrenze
- typische Fazies
- (2601250 / 1136320)
- <p>Typlokalität der Rohrbachstein-Bank und der Col-de-la-Plaine-Morte-Bank (Föllmi et al. 2007)</p>
-
Col de la Plaine Morte - Rohrbachstein (VS/BE)
- Typusprofil
-
-
Col de la Plaine Morte - Rohrbachstein (VS/BE)
Particularités du site- Obergrenze
- Untergrenze
- typische Fazies
- (2601250 / 1136320)
- <p>Typlokalität der Rohrbachstein-Bank und der Col-de-la-Plaine-Morte-Bank (Föllmi et al. 2007)</p>
-
Col de la Plaine Morte - Rohrbachstein (VS/BE)
Paléogéographie et tectonique
-
- Crétacé de l'Helvétique
- Paléogéographie
-
plateforme nord téthysienne
:
marge continentale européenne - Termes génériques
- Type de protolithe
-
- sédimentaire
- Métamorphisme
- non métamorphique
Références
- Définition
-
(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 platform-margin areas where sediments of this [Grünten] member are preserved, the top of the upper Schrattenkalk is sharply defined and marked by erosion (e.g., Gainon 2001; Hüsser 2005; Gigandet 2005; Linder et al. 2006). In the Rawil area, this surface is locally phosphatized (Fig. 8; Gainon 2001), and in the Grünten, Fronalpstock and Niederbauen areas, a cm-thin to less than a meter thick layer of glauconite-containing calcarenite rich in echinoderm debris covers the same surface (Gigandet 2005; Hüsser 2005; Linder et al. 2006). We propose to name this unit Rohrbachstein Bed or surface in the case only a phosphatized surface is present, and as type locality we define the outcrop of the Grünten Member north of the “Col de la Plaine Morte” and west of the Rohrbachstein mountain (Rawil area; Schaub 1936; Gainon 2001; Linder et al. 2006; 601’250/136’320/2540). The Rohrbachstein surface or bed is interpreted as the result of a drowning phase. In outer shelf areas beyond the carbonate platform, the Grünten Member rests directly on top of the Tierwis Formation and the drowning unconformity is less conspicuous.
- Révision
-
(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 Rohrbachstein Bed
The first layer – the Rohrbachstein Bed – marks the boundary between the top of the Urgonian Schrattenkalk Formation and the overlying Grünten Member. The top of the Schrattenkalk Formation is developed as a firm- or hardground, which is partly eroded. In Allgäu, the Rohrbachstein Bed is composed of a 10-cm thick coarsely-grained glauconitic sandstone rich in pyrite. In the Oberbauen region, the Rohrbachstein Bed attains a maximal thickness of around two meters and consists of a coarsely-grained crinoidal limestone containing various amounts of quartz sand, glauconite, and reworked extraclasts from the underlying Schrattenkalk
Formation (“Basisbreccie” of Fichter 1934). Belemnites, oysters, and rare ammonites occur within this bed (Fichter 1934; Linder et al. 2006). The upper boundary of the Rohrbachstein Bed is defined by a rapid transition into finer-grained, partly marly crinoidal limestone of the lower Grünten Beds. It is interpreted as a transgressive lag deposit, which is well distinguishable in the field. In the region of the Col de la Plaine Mort, the hardground on top of the Schrattenkalk Formation is covered by phosphatic patches, which are considered as an equivalent of the Rohrbachstein Bed (Föllmi & Gainon 2008).
The Rohrbachstein Bed is important as it documents the drowning of the Schrattenkalk Formation marked by the installation of a hardground, phosphogenesis and glauconite formation, erosion and sediment reworking, and the importation of detrital quartz. It signals the final disappearance of photozoan
carbonate production, and shows that carbonate production came to a complete halt, before it took up again in a heterozoan mode, as documented by the lower Grünten Beds. The presence of belemnites and rare ammonites suggests relative sea-level rise associated with the drowning event and the emplacement of the Rohrbachstein Bed. Its age is near the boundary between the weissi and deshayesi ammonite zones. (...)
- Principales publications
-
(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(2007) : Unlocking paleo- environmental information from Early Cretaceous shelf sediments in the Helvetic Alps: stratigraphy is the key! Swiss J. Geosci. 100, 349-369