«Granulosa-Kalk»

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Représentation et statut

Couleur CMYK
N/A
Couleur RGB
R: 120 G: 120 B: 120
Rang
unité lithostratigraphique
Usage
Ce terme n'est pas en usage.
Status
terme incorrect (mais utilisé de manière informelle)

Nomenclature

Deutsch
«Granulosa-Kalk»
Français
«Calcaire à Assilina granulosa»
Italiano
«Calcare a Assilina granulosa»
English
«Granulosa Limestone»
Origine du nom

Namengebendes Fossil: Foraminiferenart Assilina granulosa. Diese Art ist jedoch bis ins Dach des Einsiedeln-Members vorhanden.

Variantes historiques

roter Assilinenkalk (Arn. Heim 1908), roter Kalk mit Assilina granulosa = Granulosakalk (Jeannet et al. 1935), Granulosa-Murchisonikalk = hämatitischer Nummulitenkalk mit Assilina granulosa (Ochsner 1975), Granulosa Limestone and Marl (Lihou 1995)

Description

Description

Der Granulosa-Kalk besteht aus einem blaugrauen Kalk und einem roten, hämatitischen Kalk mit Assilina granulosa.

Épaisseur
0,75 - 2 m ; 2 m am Sihlsee (Jeannet et al. 1935)

Composants

Fossiles
  • assilines

Assilina granulosa

Hiérarchie et succession

Unités sus-jacentes

Âge

Âge au sommet
  • Yprésien tardif
Âge à la base
  • Yprésien moyen
Note sur la base

Cuisien moyen (Lihou 1995)

Paléogéographie et tectonique

  • Tertiaire
Paléogéographie
plateforme nord téthysienne :
marge continentale européenne
Termes génériques
Type de protolithe
  • sédimentaire
Conditions de formation

neritisch

Métamorphisme
non métamorphique

Références

Définition
Heim Arnold (1908) : Die Nummuliten- und Flyschbildungen der Schweizeralpen. Versuch zu einer Revision der alpinen Eocaen-Stratigraphie. Abh. Schweiz. Paläont. Ges. 35/4
Révision
Lihou Joanne C. (1995) : A new look at the Blattengrat unit of eastern Switzerland: Early Tertiary foreland basin sediments from the south Helvetic realm Eclogae geol. Helv. 88/1, 91-114

p.104: In most profiles, the Murchisoni horizon passes directly into the Granulosa Limestone and Marl, which was named after its index foraminifera, Assilina granulosa. It consists of two marls of varying thickness (0.2-0.5 m) separated by a brecciated limestone or calcareous greensand. At Lower Sibetsegg (733.7/197.7) (Wegmann 1961) and Näserinabach (Fig. 5), both the limestone and marls contain a fauna of abundant assilinids, small nummulitids and discocyclinids, which implies a water depth of more than 50 m according to Racey (1988). The marls provide good correlation surfaces, in particular the second marl which coincides with the disappearance of Nummulites murchisoni at the base of the main Nummulitic Limestone. The lower marl in Näserinabach is much thicker than elsewhere and contains silty lenses with pyritised assilinids and echinoderms, produced by bioturbation within a sediment column that became a reducing environment further down.

At Upper Windegg, there is evidence of a third phase of early cementation in the form of a nodular limestone horizon at the top of the Granulosa Limestone (Fig. 4). The fine sandy limestone nodules and medium-sized assilinids imply that fine material has been winnowed out and the remainder lithified by through-going pore fluids. A similar nodular limestone is present in the Fanenstock profile where there is no marl at all, and is colonised by bryozoans (Fig. 4).
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