«Knollen-Bank»

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Rappresentazione e statuto

Colore CMYK
siehe Villigen-Formation
Colore RGB
R: 185 G: 195 B: 215
Rango
Strato litostratigrafico
Uso
Unità in uso.
Status
termine informale

Nomenclatura

Deutsch
«Knollen-Bank»
Français
«Knollen-Bank»
Italiano
«Knollen-Bank»
English
«Knollen Bed»
Varianti storiche

Knollenbank (Moesch 1863), Knollenschicht (Moesch 1867, Tobler 1905 Tab.4a), Knollenbank (Moesch 1867), Knollenschichten (Hantke 1967), Knollen Bed (Gygi ----)

Nota sul nome

cf. “bauhini-Faunenhorizont” (Schweigert & Callomon 1997)

Descrizione

Descrizione

Dünner, leicht glaukonitischer Leithorizont an der Grenze zwischen Wangen- und Letzi-Member, bzw. zwischen Küssaburg- und Wangental-Member (innerhalb der Villigen-Formation).

Potenza
einige Dezimeter mächtig (Gygi 2000c)

Componenti

Minerali
  • glauconite
Fossili
  • spugne
  • bivalvi

Pectiniten

Gerarchia e successione

Unità di rango superiore
Unità sovrastante
Unità sottostante
Limite superiore

Wangental-Member bwz. Letzi-Member

Limite inferiore

Küssaburg-Member bzw. Wangen-Member

Età

Geomorfologia
  • Primo Kimmeridgiano
Età alla base
  • Oxfordiano tardo
Metodo di datazione

Biostratigraphie: Ammoniten der Zone à Planula (Enay et al. 1988).

Geografia

Estensione geografica
Aargauer und Solothurner Jura, Klettgau, Randen, Süddeutschland (Balingen).
Sezione-tipo
  • Schrannechopf (AG)
    Caratteristiche del sito
    • Obergrenze
    • Untergrenze
    • typische Fazies
    Agibilità del sito
    • Strassenanschnitt / Bahnanschnitt
    Coordinate
    • (2657700 / 1264070)
    Nota
    • Strasse östlich Villiger Geissberg auf Kote 525 m (Gygi 1969 Pl. 17 Profil RG62, Gygi et al. 1998 Fig.12, Gygi 2000c)

Paleogeografia e tettonica

  • Malm (Jura)
Paleogeografia
Swabian Basin
Termini generici
Tipo di origine
  • sedimentaria
Condizioni di formazione

"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.163
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.134: Knollen Bed (Moesch 1863) ; Marker bed within the Villigen Formation Moesch (1863. p. 163) discerned this excellent marker bed (Knollenbank) between the Wangen Member below and the Letzi Member of Canton Aargau above for the first time. He did not designate a type locality. The best outcrop of the marker bed is west of Villigen, Canton Aargau. LK 1070 Baden, in section RG 62 at the locality Schrannechopf that is not mentioned on the map. The road that leads from Villigen to Mt. Geissberg cuts across the almost horizontal Knollen Bed (Knollenschicht of Moesch 1867. p. 169) at the bend of the road at coordinates 657.700/264.070 at an elevation of 525 m. The outcrop was figured by Gygi et al. (1998. Fig. 12). The photograph shows the upper part of bed 58 of section RG 62 and bed 59. The uppermost 10 cm of bed 58 is made up of corroded limestone nodules several centimeters across that are embedded in a marly glauconitic matrix. In the uppermost 20 cm of bed 58 and in the overlying bed 59 there are limonite nodules (primarily iron sulfide) with a diameter of up to several centimeters. Bed 59 has a slight content of fine-grained glauconite. The nodular upper part of bed 58 and bed 59 with many pectinid bivalves with a limonitic crust are the Knollen Bed with a total thickness of 30 cm. Section RG 62 (PI. 17 in Gygi 1969) is the type section. The Knollen Bed is normally only a few decimeters thick and contains some fine-grained glauconite. Where it includes many siliceous sponges, its thickness can increase to form low sponge bioherms. Bioherms were found in the large quarry of Mellikon in Canton Aargau. north of the ruin of Küssaburg as well as near Immendingen and Möhringen in southern Germany (Gygi 1969. Pl. 19). It is probable that Schweigert & Callomon (1997. p. 27) found Amoeboceras bauhini (Oppel) in the Knollen Bed in the quarry on Mt. Plettenberg 7 km southwest of Balingen, southern Germany and that the Knollen Bed is at the base of the Kimmeridgian Stage. The Knollen Bed can be traced from Schönenwerd in Canton Solothurn (west of Aarau) through Canton Aargau. the Klettgau. Randen in Canton Schaffhausen as far as the area near Balingen in southern Germany over a distance of 120 km (Gygi 1969. p. 57). The base of the Knollen Bed is sequence boundary O 8 of Gygi et al. (1998).
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