Cenomanian

The Cenomanian (usually shortened as Cenomanian called ) is in Earth's history, the lowest stratigraphic stage of the Upper Cretaceous. The stage includes geochronological the period from about 100.5 to about 93.9 million years. The Cenomanian following the Albian ( Lower Cretaceous ) and is detached from the Turonian.

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

Naming and history

The original type locality is located near Le Mans (Dept. Sarthe, France). The (new ) Latin name of Le Mans is Cenomanum and which of the stages name is formed. Name and geological level suggested by Alcide Dessalines d' Orbigny, 1847.

Definition and GSSP

The base of the stage is defined by the first appearance of foraminiferal species Rotalipora globotruncanoides. The stage ends with the first appearance of the ammonite species Watinoceras devonense. Important index fossils for the Cenomanian are the ammonite species Calycoceras navicular, Acanthoceras rhotomagense and Mantelliceras mantelli. The GSSP ( global calibration point ) is located 36 m below the top of the Marnes Bleues - formation at Mont Risou, Rosans, Hautes-Alpes department in southeastern France (44 ° 23'33 " N, 5 ° 30'43 " E).