Crenularis-Member

Rappresentazione e statuto

Colore CMYK

cf. Villigen-Formation

Colore RGB

R: 185 G: 195 B: 215

Rango

Membro litostratigrafico (Sotto-formazione)

Uso

Unità in uso.

Status

termine formale valido

Nomenclatura

Deutsch

Crenularis-Member

Français

Membre à Crenularis

Italiano

Membro a Crenularis

English

Crenularis Member

Origine del nome

Namengebendes Fossil: Echinoidenart Hemicidaris crenularis (Lamarck) Agassiz.

Varianti storiche

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

Descrizione

Descrizione

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

Potenza

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

Componenti

• glauconite

• spugne
• echinoidi
• bivalvi

Pholadomya

Gerarchia e successione

Unità di rango superiore

• Villigen-Formation

Unità sovrastante

• Wangen-Member (sensu Gygi 1969)

Unità sottostante

• Geissberg-Member

Osservazioni sulla stratigrafia

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.

Età

Geomorfologia

• Oxfordiano tardo

Età alla base

• Oxfordiano tardo

Metodo di datazione

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

Geografia

Estensione geografica

Von Oftringen im Westen bis Lägern im Osten und im Aargauer Tafel-Jura.

Regione-tipo

Aargauer Jura

Località-tipo

• Villiger Geissberg (AG)
  Caratteristiche del sito
  • typische Fazies
  Agibilità del sito
  • Strassenanschnitt / Bahnanschnitt
  Coordinate
  • (2657785 / 1264055)
  Nota
  • Kote 510 m (Gygi 1969 S.69 Profil RG62), Kompositprofil

Sezione-tipo

• Villiger Geissberg (AG)
  Caratteristiche del sito
  • typische Fazies
  Agibilità del sito
  • Strassenanschnitt / Bahnanschnitt
  Coordinate
  • (2657785 / 1264055)
  Nota
  • Kote 510 m (Gygi 1969 S.69 Profil RG62), Kompositprofil

Sezione di riferimento

• Gabenchopf (AG)
  Caratteristiche del sito
  • typische Fazies
  Agibilità del sito
  • Steinbruch, Tongrube
  Coordinate
  • (2656965 / 1265050)
  Nota
  • 2 km NW Villigen (Gygi 2000c)

Paleogeografia e tettonica

• Malm (Jura)

Paleogeografia

Argovian Basin

Termini generici

• Jura :
  Juragebirge

Tipo di origine

• sedimentaria

Condizioni di formazione

"argovien" / "séquanien"

Metamorfismo

non metamorfo

Referenze

Definizione

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

S.157

Revisione

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).