Geissberg-Member

Representation and status

Index

i6G

Color CMYK

siehe Villigen-Formation

Color RGB

R: 185 G: 195 B: 215

Rank

lithostratigraphic Member (Subformation)

Validity

Unit is in Use

Status

valid formal name

Status discussion

Nomenclature

Deutsch

Geissberg-Member

Français

Membre du Geissberg

Italiano

Membro del Geissberg

English

Geissberg Member

Origin of the Name

Geissberg (AG) bei Villigen

Historical Variants

Geissbergschichten p.p. (Moesch 1857 S.57), Geissbergschichten emend. (Moesch 1867 S.145, Tobler 1905 Tab.4a/5b, Baltzer 1906, Disler 1941, Hantke 1967), couches du Geissberge (de Tribolet 1872, BRGM-Doubs), Couches du Geissberg (de Tribolet 1873, Dreyfuss et al. 1956, Donzeau et al. 1997, Brentini 2018), Couches à Pholadomya pelagica = couches du Geissberg (Rollier 1888a), Argovien supérieur = Couches du Geissberg (Rollier 1910), Couches de Geissberg (Enay 1966, Charollais et al. 2013), Geissberg Member (Gygi 2000c), Geissberg-Schichten

Links

Synonyms

«Calcaire à Cardium»

Description

Description

Gebankte, kompakte, mikritische Kalksteine in Bänken von 10 cm bis 30 cm mit Mergelzwischenlagen von 2 cm bis 5 cm. Das Geissberg-Member zeigt keine scharfe Grenze zu dem liegenden Effingen-Member.

Thickness

Ca. 15 - 20 m am Geissberg (Gygi 2000c)

Components

• ammonites
• bivalves

Lithacosphinctes (Mühlberg 1908), Myacées

Hierarchy and sequence

Superordinate unit

• Villigen-Formation

Units at roof

• Calcaires lités
• Crenularis-Member

Units at floor

• Effingen-Member

Upper boundary

Crenularis-Member

Lower boundary

Unscharfe Grenze mit Effingen-Member: graduelle Zunahme des Karbonatanteils und der Dicke der Bänke (transgressive surface between sequence boundaries Ox6 and Ox7 ; Wetzel & Strasser 2001).

Age

Age at top

• late Oxfordian

Age at base

• late Oxfordian

Dating Method

Biostratigraphie: Ammoniten der Berrense-Zone (Gygi 2012) oder Bimammatum-Zone (Enay 1966). Bifurcatum-Zone im südlichen Jura (Enay et al. 1988).

Geography

Geographical extent

Aargauer Jura

Type area

Nördlicher Kt. Aargau

Type locality

• Geissberg (AG), bei Villigen
  Site particularities
  • typische Fazies
  Site accessibility
  • Grat
  Coordinates
  • (2655000 / 1264400)
  Note
  • Chamerenfelsen am Westende des Geissbergs (Moesch 1857 S.57, Gygi 2000c)

Type profile

• Gabenchopf (AG)
  Site particularities
  • typische Fazies
  Site accessibility
  • Steinbruch, Tongrube
  Coordinates
  • (2656650 / 1265050)
  Note
  • Steinbruch Gabenchopf am Geissberg (Gygi 2000c als Referenzprofil definiert ; Wetzel & Strasser 2001)

Point of interest

• Ob Chilen (AG) bei Villigen
  Site particularities
  • Obergrenze
  • Untergrenze
  • typische Fazies
  Site accessibility
  • Bachprofil
  Coordinates
  • (2658055 / 1264245)
  Note
  • Ob Chilen = Ob. der Kirche (Gygi 1969 Pl.19 Profil RG63, Gygi 2000c)

Palaenography and tectonic

• Malm

Paleogeography

Argovian Basin

Tectonic unit (resp. main category)

• Jura :
  Juragebirge

Kind of protolith

• sedimentary

Conditions of formation

Beckenfazies («argovien» ; represent the marginal part of the carbonate platform). Most of the beds are carbonate-rich tempestites which contain some shallow-water material. Further up, several packages of limestone beds can be distinguished; 42 m of micrite contain shallow-water biodetritus, commonly enriched in nests which are of biogenic or physical origin. The content in bioclasts steadily increases upward, pointing to a progradation of the platform. (Wetzel & Strasser 2001).

Metamorphism

non metamorphic

References

Definition

Moesch Casimir (1857) : Das Flötzgebirge im Kanton Aargau. Neue Denkschr. schweiz. natf. Ges. 15

... complexe schisteux compris entre les couches d'Effingen et celles de Baden.

Definition

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.130: Geissberg Member (Moesch 1867) ; Member of the Villigen Formation The Geissberg lithostratigraphical unit (Geissbergschichten) was named by Moesch (1857. p. 57) and then encompassed all the limestone members included in the Villigen Formation sensu Gygi & Persoz (1986. p. 407) between the Effingen Member below and the Baden Member above. Moesch (1867 p. 145) restricted the unit to the rank of what is today a member and conceived it as the thickly bedded micritic limestones between the marly Effingen Member below and the glauconitic Crenularis Member above. According to Moesch (1857 p. 57). the cliff above the southern slope at the western end of Mt. Geissberg west of Villigen. Canton Aargau. must be considered to be the type locality of what is at present the Geissberg Member. This cliff is now called Chamerenfelsen and is located at coordinates 655.000/264.400. LK 1069 Frick. The thickness of the Geissberg Member at Mt. Geissberg near Villigen in the large quarry on the north slope of Mt. Geissberg, west of Gabenchopf near Villigen, is between 15 and 20 m. This quarry (coordinates ca. 656.650/265.050. LK 1070 Baden) is now considered to be the reference section of the Geissberg Member. An entire section of the member is also in the natural outcrop of the gully south of the part of the village Villigen called Ob Chilen. This is section RG 63 that is schematically represented in Gygi (1969. Pl. 19). The great thickness of the Geissberg Member near Baden (Gygi 1969 Pl. 19) is exceptional. The macrofossils ofthe Geissberg Member are mostly bivalves, but large ammonites of the genus Lithacosphinctes occur too (Mühlberg. 1908. p. 43). The Geissberg Member is delimited in the west by the Olten Member. In the northeast it grades into the lower Hornbuck Member (Fig.1).