Membre de Sornetan

Representation and status

Index

i4-5S

Color CMYK

cf. Formation de Bärschwil

Color RGB

R: 170 G: 175 B: 120

Rank

lithostratigraphic Member (Subformation)

Validity

Unit is in Use

Status

valid formal name

Status discussion

Nomenclature

Deutsch

Sornetan-Member

Français

Membre de Sornetan

Italiano

Membro di Sornetan

English

Sornetan Member

Origin of the Name

Gorges du Pichoux au nord-ouest de Sornetan (BE)

Historical Variants

«Terrain à chailles» auct., Sornetan Member (Gygi 2000b, Gygi 2000c), Membre de Sornetan (Aufranc et al. 2017)

Description

Description

Grauer, mergeliger Ton mit Lagen von Kalkkonkretionen, die nach oben häufiger werden, führt Ammoniten, Bivalven, Echiniden, Crinoiden.

Thickness

46 m bei Liesberg, 37,5 m in Anwil.

Components

• ammonites
• crinoids
• belemnites
• echinoids
• bivalves

Pholadomyen

Hierarchy and sequence

Superordinate unit

• Bärschwil-Formation

Units at roof

• Liesberg-Member

Units at floor

• Renggeri-Member

Upper boundary

L'apparition des premiers coraux définit la base du Mb. de Liesberg sus-jacent.

Lower boundary

Passage progressif.

Age

Age at top

• middle Oxfordian

Age at base

• middle Oxfordian

Dating Method

Ammonites: Zones à Cordatum et à Transversarium-Zone (Gygi & Marchand 1993, Gygi 1995)

Geography

Geographical extent

NW-Schweiz, siehe Karte Gygi 1990c, Fig. 2 - 4

Type area

NW Schweiz

Type profile

• Gorges du Pichoux, en rive orientale de la Sorne, 1,5 km N-E Sornetan
  Site particularities
  • typische Fazies
  Coordinates
  • (2584169 / 1237100)
  Note
  • Gygi 2000b, profil RG 314, Pl.21

Reference profiles

• Hinter Chestel (BL)
  Site particularities
  • Obergrenze
  • Untergrenze
  • typische Fazies
  Site accessibility
  • Steinbruch, Tongrube
  Coordinates
  • (2599550 / 1249500)
  Note
  • Gygi 2000b, Profil RG-306, Pl.21

Point of interest

• Etang du Bois du Roy, NE Trévillers
  Site particularities
  • Untergrenze
  • typische Fazies
  Coordinates
  • (2557900 / 1237440)
  Note
  • Aufranc et al. 2016

Palaenography and tectonic

• Malm

Tectonic unit (resp. main category)

• Jura :
  Juragebirge

Kind of protolith

• sedimentary

Sequence

Within this interval, the content in fossil debris slightly increases up to the so-called “fossil-rich bed”, which is located roughly in the middle of the Terrain à Chailles. [...] In the mud-dominated

Terrain à Chailles, maximum quartz content as well as

abundant serpulids appear to characterize SB Ox3. Levels

rich in ferroan calcite cement and glauconite indicating slow

sedimentation are interpreted as flooding or maximum-flooding

surfaces. (Wetzel & Strasser 2001)

Metamorphism

non metamorphic

References

Definition

Gygi R. A. (2000) : Integrated stratigraphy of the Oxfordian and Kimmeridgian (Late Jurassic) in northern Switzerland and adjacent southern Germany. Denkschriften der Schweizerischen Akademie der Naturwissenschaften 104, 152 S.

p.53

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.127: The Sornetan Member in the middle is a gray marl with ellipsoidal carbonate nodules, ammonites and bivalves, about 45 m thick.

p.140