Kimmeridgian

The Kimmeridgian ( in German often shortened to Kimmeridge, rarely also Kimmeridgien ) is in the geologic timescale, middle stage of the Upper Jurassic in the Jura. Geochronological the stage started about 157.3 million years ago and ended 152 100 000 years. The Kimmeridgian follows the Oxfordian; after the Kimmeridgian comes the Tithonian.

Naming and history

The term " Kimmeridgien " was introduced by Jules Thurmann 1832. It involves the Latinized name of the village Kimmeridge, on the Isle of Purbeck, in the county of Dorset on the English Channel coast of England.

Definition and GSSP

The stage begins with the layers in which the first ammonite species Pictonia baylei occurs. The end of the stage is defined by the onset of the Ammonites Hybonoticeras hybonotum. The end of the stage and is coincident with the magnetic anomaly M22An. A GSSP (global type locality and type profile ) has not yet been determined.

Subdivision

The Kimmeridgian is subdivided in the Tethyan region in seven ammonite biozones:

  • Hybonoticeras beckeri
  • Aulacostephanus Eudoxus
  • Aspidoceras acanthicum
  • Crussoliceras divisum
  • Ataxioceras hypselocyclum
  • Sutneria platynota
  • Idoceras planula

The Kimmeridgian is divided into the lower and Oberkimmeridgium.

Mya (unit) Oxfordian (stage) Pliensbachian History of the Earth Counties of England
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