Turonian

The Turonian ( often shortened in the German language to Turonian ) is in Earth's history, a chronostratigraphic stage of the Upper Cretaceous. The Turonian began geochronological before about 93.9 million years ago and ended about 89.7 million years. The Turonian followed the Cenomanian, it closes the Coniacian to.

At the beginning of an oceanic anoxic event Turoniums took place, which was named after its first describer Livello Bonarelli closely. " Cenomanian Turonian Boundary Event ".

Naming and history

The original eponymous type locality of this stage is located in the French countryside in Touraine near the French city of Tours (Dept. Indre -et -Loire, France). The Latin name of the landscape is Turonia. The stage and its name was suggested by Alcide Dessalines d' Orbigny, 1842.

Definition and GSSP

The beginning of the stage is defined by the Ersteinsetzen the ammonite species Watinoceras devonense. The border to the Coniacian, the subsequent step, by the first appearance of inoceramids Type Cremnoceramus rotundatus. The GSSP (global type locality and type section) is located in the Rock Canyon Anticline, west of Pueblo, Colorado, USA (coordinates: 38 ° 16 ' 56 "N, 104 ° 43' 39" W).

Subdivision

The Turonian can be divided into sub- levels lower, middle and Oberturon.

For the Tethysbereich following biostratigraphic ammonite zones are eliminated:

In Oberturon:

  • Subprionocyclus neptuni

In Mittelturon:

  • Collignoniceras woollgari

In Unterturon:

  • Mammites - nodosoides zone
  • Watinoceras - coloradoense zone or Watinoceras devonense

Fossils

Important index fossils of Turons following inoceramids ( shells ): Inoceramus schloenbachi, Inoceramus Inoceramus lamarcki and labiatus.

Mya (unit) Danian Maastrichtian Campanian Santonian Albian Aptian Barremian Hauterivian Valanginian History of the Earth Inoceramidae
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