Toarcian (184.2 +/-0.3 Ma)

Back to Early Jurassic (201.3 +/-0.2 Ma)

Representation and status

Index
toa
Color CMYK
40 / 5 / 0 / 0
Color RGB
R: 153 G: 206 B: 227
Rank
chronostratigraphic Stage
Validity
Unit is in Use
Status
valid formal name
Status discussion

Nomenclature

Deutsch
Toarcien (CH) (DE/AT: Toarcium / Toarc)
Français
Toarcien
Italiano
Toarciano
English
Toarcian (184.2 +/-0.3 Ma)
Origin of the Name

Named after the town of Thouars (Deux-Sèvres, France), south of Saumur. The protected stratotype lies in an old quarry. Its GSSP is located at Peniche (Portugal).

Historical Variants

Lias supérieur (d'Orbigny 1842), Toarcien (d'Orbigny 1849), Thouarsien (Mayer-Eymar 1864, Mouterde 1956), 12e Etage = Toarcien (Greppin 1866)

Nomenclatorial Remarks

Latin: Toarcium

Hierarchy and sequence

Subordinate units
Units at roof
Upper boundary

Top lies just below the first appearance of the ammonite genus Leioceras.

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.

Age

Age at top
  • Toarcian
Age at base
  • Toarcian

Geography

Type area
Deux-Sèvres (Paris Basin, France)
Type profile
  • Carrière de Vrines (Deux-Sèvres), près de Thouars
    Site particularities
    • typische Fazies
    Site accessibility
    • geschützter Geotop
    Note
    • <p>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.</p>
Reference profiles

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.

Material and varia

Images
Thouars_loctyp

  • Late Toarcian

    Rank
    chronostratigraphic Substage
    Status
    valid formal name
    Age
    late Toarcian
    Show details

  • Middle Toarcian

    Rank
    chronostratigraphic Substage
    Status
    valid formal name
    In short
    The Middle Toarcian is defined biostratigraphically by the ammonite genera Hildoceras and Haugia.
    Age
    middle Toarcian
    Show details

  • Early Toarcian

    Rank
    chronostratigraphic Substage
    Status
    valid formal 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
    Show details

    • Toarcian Oceanic Anoxic Event

      Rank
      Oceanic Anoxic Event
      Status
      informal term
      In short

      Major oceanic anoxic event of the Early Toarcian (around 183 Ma ago), documented by black shale deposits found on all major continents (no oceanic drilling cores have recovered black shales of this age as there is little or no Toarcian ocean crust remaining in the world ocean). This event correlates with a marine extinction event.

      Show details
Back to top
This site or embedded third-party content uses cookies.
This site or embedded third-party content uses cookies, but we respect your 'Do Not Track' browser setting, which is currently enabled!
Close menu