«Murchisoni-Kalk»
Torna a Einsiedeln-MemberRappresentazione e statuto
- Colore CMYK
- N/A
- Colore RGB
- R: 120 G: 120 B: 120
- Rango
- unità litostratigrafia
- Uso
- Unità non usata
- Status
- termine scorretto (informale)
Nomenclatura
- Deutsch
- «Murchisoni-Kalk»
- Français
- «Calcaire à Nummulites murchisoni»
- Italiano
- «Calcare a Nummulites murchisoni»
- English
- «Murchisoni Limestone»
- Origine del nome
-
Namengebendes Fossil: Foraminiferenart Nummulites murchisoni. Diese Art ist jedoch bis im unteren Teil des «Grauen Nummulitenkalks» vorhanden.
- Varianti storiche
-
Murchisonikalk = Murchisonkalk [sic] (Jeannet et al. 1935), Granulosa-Murchisonikalk (Ochsner 1975), Murchisoni horizon (Lihou 1995), Nummulitenkalk
Descrizione
- Potenza
- 1,1 - 2 m ; 1,6m am Sihlsee (Jeannet et al. 1935)
Componenti
- glauconite
- nummuliti
Nummulites "Murchisoni"
Gerarchia e successione
- Unità sovrastante
Età
- Geomorfologia
-
- tardo Ypresiano
- Età alla base
-
- Ypresiano medio
Paleogeografia e tettonica
-
- Terziario
- Paleogeografia
-
North Tethyan Shelf (Helv.)
:
marge continentale européenne - Termini generici
-
-
Östliches Helvetikum
:
u.a. Glarner Alpen
-
Östliches Helvetikum
:
- Tipo di origine
-
- sedimentaria
- Condizioni di formazione
-
neritisch
- Metamorfismo
- non metamorfo
Referenze
- Revisione
-
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: The first hardground in the Nummulitic Limestone marks the base of the Murchisoni horizon, named after the common occurrence of Nummulites murchisoni, a lower to middle Cuisian nummulite (Schaub 1981). In Weisstannental, the Murchisoni horizon is represented by a calcareous greensand with echinoderm debris, that passes southeastwards into a sandy limestone at Gula-Schwamm (Fig. 5). East of Elm, the same stratigraphic horizon thickens to the south and passes into a limestone-rich facies in the Fanenstock profile (Fig. 4). There, the hardground is overlain by a limestone breccia containing Operculina sp. and Globigerina sp.; whilst Operculina sp. inhabits a range of water depths (0-130 m) (Murray 1991), globigerinids are rare at depths of less than 40 m, and only abundant above 80-100 m (Brasier 1980). The limestone breccia passes upwards into a glauconitic foraminiferal limestone with very big nummulitids and discocyclinids; the bias towards large B-form nummulitids either arose by winnowing out of smaller A-forms by bottom currents, or selective transport of larger forms during high energy storm events (Crampton 1992). In situ faunas are dominated by A-forms in an A:B ratio of 10:1 (Blondeau 1972).