Toarcian (~ 183 Ma)

Back to the list

Representation and status

Index
toa
CMYK Color
40 / 5 / 0 / 0
RGB color
R: 153 G: 206 B: 227
Rank
chronostratigraphic Stage
Validity
Unit is in Use
Status
valid formal name
SCS note
-
SCS date
-
Comment
Originally (d'Orbigny 1849), the Toarcian encompassed the whole Aalenian and part of the Bajocian as well.

Nomenclature

German
Toarcien (CH) (DE/AT: Toarcium / Toarc)
French
Toarcien
Italian
Toarciano
English
Toarcian (~ 183 Ma)
Origin of the Name

Named after the town of Thouars (Deux-Sèvres, France), S Saumur. The protected stratotype lies in an old quarry.

Historical Variants
Lias supérieur (d'Orbigny 1842), Toarcien (d'Orbigny 1849), Thouarsien (Mayer-Eymar 1864)
Nomenclatorial Remarks
-

Synonyms

Synonyms
Non-synonyms
Possible confusion

Description

Description
-
Geomorphology
-
Thickness
-

Components

Lithological content
-
Mineral content
-
Fossil content
-

Hierarchy and succession

Superordinate unit
Subordinate units
Units at roof
    -
Units at floor
Lateral equivalents
Upper boundary
-
Lower boundary
Base defined by the first appearance of Eodactylites mirabile (Tethyan Realm), or alternatively by the mass appearance of other dactylioceratids together with Paltarpites paltus.
Stratigraphic discussion
-

Age

Age at top
Toarcian
Note about top
-
Age at base
Toarcian
Note about base
-
Dating method
-

Geography

Geographical extent
-
Type area
Type locality
-
Type profile
  • carrière de Vrines, Thouars
    Site particularities
    • typical facies
    Site accessibility
    • protected geotope
    Coordinates
    • (- / -)
    Note
    • Proposed by d'Orbigny (1849) and further studied by Eudes-Deslongchamps and Welsch. Detailed biostratigraphy by Gabilly (1976), who pointed out the condensed nature (7 m altogether) of the section and the incompleteness of the record at the base.
  • Ponto do Trovao, Peniche (Portugal)
    Site particularities
    • lower boundary
    Coordinates
    • (- / -)
    Note
    • GSSP proposal: base defined by the appearance of the ammonite species Eodactylites polymorphum.
Reference profiles
Point of interest
-

Paleogeography and tectonic

Paleogeography
-
Kind of protolith
-
Conditions of formation
-
Sequence
-
Tectonic Unit (resp. main category)
Time Scale
  • Paratethys
  • Mammal stages
Metamorphism
-
Metamorphic facies
-
Note on metamorphism
-

References

Definition
d'Orbigny A. (1846): Foraminifères fossiles du bassin tertiaire de Vienne (Autriche). , Gide, Paris

Ce nom dérive de la ville de Thouars (Toarcium) (Deux-Sèvres), où l'on ne trouve que cet étage sur les roches aszoïques; où il a le plus beau développement en France et peut être regardé comme point type, point étalon. C'est la zone du Lima gigantea et de l'Ammonites bifrons.
Revision
-
Important publications
-

Material and varia

Applications
-
Historical stratotype of the Toarcian stage at Thouars (Deux-Sèvres, France) (14.09.2001 – A. Morard)..
Historical stratotype of the Toarcian stage at Thouars (Deux-Sèvres, France) (14.09.2001 – A. Morard)..
Candidate GSSP at Peniche, Portugal (06.10.2005 - A. Morard).
Candidate GSSP at Peniche, Portugal (06.10.2005 - A. Morard).
  • Late Toarcian Show details

    Origin of the Name
    -
    Rank
    chronostratigraphic Substage
    Status
    valid formal name
    Valid name
    In Short
    -
    Age
    late Toarcian - late Toarcian
    Thickness
    -
    Geographical extent
    -
    Type area
    -
    Comment
    -
  • Middle Toarcian Show details

    Origin of the Name
    -
    Rank
    chronostratigraphic Substage
    Status
    valid formal name
    Valid name
    In Short
    The Middle Toarcian is defined biostratigraphically by the ammonite genera Hildoceras and Haugia.
    Age
    middle Toarcian - middle Toarcian
    Thickness
    -
    Geographical extent
    -
    Type area
    -
    Comment
    The Middle Toarcian is rather poorly documented in Switzerland. When present it occurs either in the younger part of the posidonia shales facies, or as a condensed horizon at the base of units of mainly Late Toarcian age. It is better developped in the rosso ammonitco facies of the Southern Alps and in the austroalpine Allgäu Fm.
  • Early Toarcian Show details

    Origin of the Name
    -
    Rank
    chronostratigraphic Substage
    Status
    valid formal name
    Valid name
    In Short
    The Early Toarcian is characterized almost worldwide by black shales (among which the well-known «Posidonienschiefer» of Southern Germany, and the French «schistes-carton») with an ammonite fauna composed mainly of dactylioceratids, harpoceratids and early hildoceratids.
    Age
    early Toarcian - early Toarcian
    Thickness
    -
    Geographical extent
    -
    Type area
    -
    Comment
    In Switzerland, the Early Toarcian is recorded as posidonia shales (e.g. Rietheim Mb. in the Swiss Jura, Couches du Creux de l'Ours of the Préalpes Médianes) or as hiatal, condensed or reworked horizons (sometimes conglomeratic such as at the base of the Mols Mb. in the Helvetic Realm or as Fe/Mg-crusts such as at the top of the austroalpine Agnelli Fm.). In the southern Alps, the rosso ammonitico facies starts during the Early Toarcian.