Crenularis-Member

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Représentation et statut

Couleur CMYK
cf. Villigen-Formation
Couleur RGB
R: 185 G: 195 B: 215
Rang
Membre lithostratigraphique (Sous-formation)
Usage
Ce terme est en usage.
Status
terme formel valide

Nomenclature

Deutsch
Crenularis-Member
Français
Membre à Crenularis
Italiano
Membro a Crenularis
English
Crenularis Member
Origine du nom

Namengebendes Fossil: Echinoidenart Hemicidaris crenularis (Lamarck) Agassiz.

Variantes historiques

Crenularisschichten (Moesch 1863 S.157, Tobler 1905 Tab.4a, Baltzer 1906, Disler 1941), couches à Hémicidaris crenularis (Boyer 1885), Crenularis Schichten = Zone à Peltoceras bicristaum p.p. (Haug 1911), Crenularis-Schichten (Hantke 1967), Crenularis Member (Gygi 2000c), Couches à Hemicidaris crenularis

Description

Description

Das Crenularis-Member besteht aus Kalksteinen. In den glaukonitischen Lagen kommen lokal Schwammnadeln vor.

Épaisseur
Ca. 3-4,5 m ; 17 m bei Mellikon in atypischer Fazies (Schwamm-Bioherm ; Gygi 1969)

Composants

Minéraux
  • glauconite
Fossiles
  • éponges
  • échinoïdes
  • bivalves

Pholadomya

Hiérarchie et succession

Unité hiérarchiquement supérieure
Unités sus-jacentes
Unités sous-jacentes
Discussion stratigraphique

Nach Gygi (1969) ist die Mächtigkeit des Crenularis-Members 17 m im Steinbruch von Mellikon, aufgrund von Schwamm-Riffen. Diese atypische Fazies markiert den Übergang zum Hornbuck-Member weiter östlich.

Âge

Âge au sommet
  • Oxfordien tardif
Âge à la base
  • Oxfordien tardif
Méthode de datation

Biostratigraphie: Ammoniten der Berrense- bis Bimammatum-Zone (Gygi 2000b/c). Bimammatum-Subzone (Enay et al. 1988).

Géographie

Extension géographique
Von Oftringen im Westen bis Lägern im Osten und im Aargauer Tafel-Jura.
Région-type
Aargauer Jura
Localité-type
  • Villiger Geissberg (AG)
    Particularités du site
    • typische Fazies
    Accessibilité du site
    • Strassenanschnitt / Bahnanschnitt
    Coordonnées
    • (2657785 / 1264055)
    Note
    • Kote 510 m (Gygi 1969 S.69 Profil RG62), Kompositprofil
Typusprofil
  • Villiger Geissberg (AG)
    Particularités du site
    • typische Fazies
    Accessibilité du site
    • Strassenanschnitt / Bahnanschnitt
    Coordonnées
    • (2657785 / 1264055)
    Note
    • Kote 510 m (Gygi 1969 S.69 Profil RG62), Kompositprofil
Coupes de référence
  • Gabenchopf (AG)
    Particularités du site
    • typische Fazies
    Accessibilité du site
    • Steinbruch, Tongrube
    Coordonnées
    • (2656965 / 1265050)
    Note
    • 2 km NW Villigen (Gygi 2000c)

Paléogéographie et tectonique

  • Malm du Jura
Paléogéographie
bassin argovien
Termes génériques
Type de protolithe
  • sédimentaire
Conditions de formation

"argovien" / "séquanien"

Métamorphisme
non métamorphique

Références

Définition
Moesch Casimir (1863) : Geologische Beschreibung des Aargauer-Jura und der nördlichen Gebiete des Kantons Zürich. Beitr. geol. Karte Schweiz 4, 349 Seiten

S.157
Révision
Gygi R. A. (2000) : Annotated index of lithostratigraphic units currently used in the Upper Jurassic of northern Switzerland. Eclogae geol. Helv. 93/1, 125-146

p.129: Crenularis Member (Moesch 1863) ; Member of the Villigen Formation Moesch (1863. p. 157) named the Crenularis Member (Crenularisschichten) that became well-known because ofthe geological maps by Mühlberg. The name is derived from the echinoid Hemicidaris crenularis (Lamarck) that rarely occurs in the member. Moesch (1863 and 1867) did not indicate a type locality. Gygi (1969. p. 69) declared his section RG 62 along the road from Villigen to Mt. Geissberg, Canton Aargau, to be the type locality of the member. The road there crosses the well-exposed Crenularis Member at the elevation of about 510 m at coordinates 657.890/264.040, LK 1070 Baden. This section is however unfavorable as a type section, because the outcrops along the road are discontinuous. The continuous section RG 62 was assembled from five partial sections that were measured on both sides of the short valley through which the road runs. The locations of the partial sections are indicated in Gygi (1969. p. 61-62). A good and complete outcrop of the typical Crenularis Member is at present accessible in the upper part of the large quarry west of Gabenchopf 2 km westnorthwest of Villigen (LK 1070 Baden). This quarry can serve as reference section.

The Crenularis Member is a biomicritic limestone with uneven bedding planes and a knobby weathering. According to Gygi (1969. Pl. 19). the mean thickness of the member is 3 m. It contains siliceous sponges and abundant bivalves, mainly of the genus Pholadomya. Ammonites are rather rare, but the mineral glauconite is always present. The member is dated biochronologically by the ammonite Epipeltoceras cf. bimammatum (Quenstedt) J 31726 in the Museum of Natural History Basel that was found by Moesch and figured by Gygi (2000b, Pl. 10. Fig. 5). The ammonite is from bed 31 in the unpublished section RG 36 of Fahr quarry at Auenstein. Canton Aargau, LK 1089 Aarau. It documents the early Bimammatum Subchron. The Crenularis Member can be followed from Oftringen, Canton Aargau in the west to east of Burghorn on Mt. Lägeren east of Baden. Canton Aargau (Gygi 1969, p. 70). In the tabular Jura of Canton Aargau it extends to Baldingen.

The thickness of the member greatly increases to 17 m near Mellikon. Canton Aargau (Gygi 1969. Pl. 17 and 19) because of the growth of sponge bioherms. This is an atypical local facies which is transitional to the Hornbuck Member in the Klettgau valley. In the proximal direction (to the west), the Crenularis Member can be traced into the lowermost Olten Member of Gygi (1969) that was also called Crenularis Member by Moesch (1867, p. 150).
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